Written for Yuletide 2014. Many thanks to my excellent beta-readers, Greenlily and Isis.

Once there was a count who ruled a castle on the edge of a forest. It was said that the Shadow Folk dwelt in the depths of that forest, in a hidden dell marked by odd twisted stones, but for the most part they did not trouble the folk of that land. The occasional missing child or strayed cow, death in childbirth or unexplained illness, was blamed on them, but nothing could be laid at their door with certainty, and only a few of the oldest men or women claimed to have seen them.

There were tales handed down, and songs sung by the bards and wandering singers, that told of a mad or ambitious or desperate man or woman who went deep into that forest, deliberately seeking out the Shadow Folk to make a bargain with them. For the most part, those tales and songs did not end happily.

The count was getting on in years, but that did not trouble him, since he had two sons to follow after him. The elder was a brave knight who had fought in many tourneys and in battle at the king's side. The younger was certainly no craven, but he did not rejoice in feats of arms, preferring to spend his time among the castle's books. He was known for his cool head and wisdom beyond his years. The count's wife had already passed away, and it seemed to him that when he went to join her, he would be leaving his people in good hands.

Matters went well enough in the count's domains, until one day the count was taken ill. The physicians and wise women did all they could, but the count only grew sicker and weaker. He put on a cheerful face, but in his heart he thought that he must die. At last they all shook their heads and said there was nothing they could do.

The count then called his two sons to his side. He bade them always help each other and entrusted his people to their care. They kissed their father's hand and sadly left the chamber.

"Alas for this illness," the younger son said, with tears in his eyes. "Our good father should have lived many years yet, but now he must leave us."

The elder son stood for a long time with his head bowed. Suddenly he spoke, saying, "I have not yet given up hope for our father's life. There is still one way left to find a cure, and I will seek it out."

"But what is that?" his younger brother asked. "The wisest and most learned of our people are at a loss."

"Do not ask, but let me go."

"My brother, you make me uneasy. If this cure is anything that should be done, why would our physicians not know of it? And why would you not tell me of it?"

"I am not certain," the elder brother said. "I do not wish to raise false hope. Tell no one of this until I return." And with that he went down to the stable and saddled his horse with his own hands.

He left the castle and rode into the depths of the wood, where the leaf-shadows dappled the ground, seeking the valley where the Shadow Folk were said to dwell. Onward he went, and at last the trees opened up before him and his horse stood at the edge of a valley. Strange rock formations guarded the way, carved by the wind into ominous shapes. The count's son left his horse at the top of the path, for he did not know what he would find. He could see an open grassy slope below him, unmarked by any sign of habitation; but as he went on he could feel a gathering in the air around him, as if many unseen folk stood watching and listening, waiting for what he might do.

He set foot on the valley floor, and in that instant the scenery changed. A fair house stood before him, capped with fantastic towers and spires, and a glow like moonlight shone from its windows and doors. The knight drew a deep breath. "I have come to speak with the Shadow Folk," he said. The bright door opened.

The knight did not see the lord of the Shadow Folk pass through the door; one moment a tall figure in the garb of a hunter stood within the threshold, and the next it was beside him.

Though they stood close enough that either could have stretched out an arm and touched the other, he could never afterward remember the hunter's face. It shifted in his memory like reflections in water when he tried to describe it. He remembered a tall slender form, a cold gaze, dark unbound hair rippling down his back. A white hound crouched at the hunter's side, and a white hawk perched on his wrist, both of a breed unknown to him. The dog and the hawk were both shining white, white as moonlight on snow, except that the ears and muzzle of the dog, and the wing-tips and tail feathers of the hawk, were all as red as if they had been dipped in blood. The dog sat watchful at his master's side, and the hawk turned her head to watch him proudly.

The hunter's eyes rested upon the knight and seemed to pierce through him, as if that lord of the Shadow Folk could read his innermost thoughts and know the desperate hope and fear that warred within him. "Why have you come?" the hunter asked. His voice was high and yet noble, like the ringing of a clarion, and his words were followed by strange echoes.

"My father the count lies ill from a lingering sickness," the knight said, "and the physicians are helpless. I have come for a cure for him."

"There is a price."

"I understand."

The hunter tilted his head. "The price is this," he said. "I will give you what will save your father's life; and in return, you will serve me for seven years in the shadow realm."

The knight bowed his head. "I agree to your terms," he said.

The hunter reached out his hand to a tree that stood near and plucked three leaves from it. "Boil these in water," he said, "strain it, and let your father drink the liquid. Within a day, he will be as well as ever."

"And he will suffer no ill effects from this herb?"

"If you do not trust the Shadow Folk, why have you come here to seek a cure? I tell you, it will not harm him. It will do only what you asked."

The knight swallowed. "Very well," he said. "I ask only that you give me time to go to the castle and save my father from his illness. Then I will return to offer you my service."

"There is no need to hasten," the hunter said indifferently. "Time does not pass for us in the shadow realm as it does for you. You may go and give the cure to your father. We will grant you time."

"How much time?" asked the knight then. "When shall I return?"

"Return to this place when you are called by the sound of this horn." He took a silver horn from his belt and blew it. The sound was sweet and mournful and eerie such as the knight had never heard, and the rocks around gave back the echoes still more shrilly and mournfully; it was such a sound as a ghost might make calling to the living. The knight shivered.

"By my knightly honor," he said, "I will come."

"Speak now the pact," the hunter commanded.

"When I hear the sound of the horn," the knight said solemnly, "I will return to this place and offer my service, to serve you in the shadow realm for seven years. I swear it, on my honor as a knight."

"I have heard your pledge and accept it. In return, I pledge to you that if you keep your word faithfully, at the end of seven years in the shadow realm I will release you, as living man and in your own shape and without baneful enchantment."

"That is well," the knight said.

He returned to his father's castle with the precious leaves clutched tightly in his hand. Once he had reached the gates, he gave his horse to a groom and wasted no time in doing as the hunter had said.

Within an hour, his father the count opened his eyes. Within a day, he was on his feet again, as hale and hearty as one would expect a man of his age to be, or even more so. All the folk of the castle rejoiced. The knight alone was sad at heart, for he expected the Shadow Folk's summons to come at any moment.

He did his best to conceal his care from the eyes of all. He was glad in truth for his father's recovery, and that made it the easier to feign untroubled pleasure. But more than once he caught his younger brother watching him intently, and he feared perhaps that he was not deceiving them as well as he thought.

He stood one evening gazing out a window, though he did not truly see what was in front of him. A hunting horn sounded gaily nearby. He started, and the blood drained from his face. The horn sounded again, with a merry flourish, and the knight realized it was not the Shadow Folk's horn, merely some hunter announcing his return.

He turned to see his brother standing nearby. "Tell me plainly what has occurred to trouble you," his brother said. "You were not wont to tremble at the sound of a hunting horn! Tell me the truth this time, and hold nothing back."

The knight felt a sudden rush of shame. If the horn had been the Shadow lord's summons, he would have had to depart at once; yet he had taken no thought for his family and his people. "Indeed, I should have told you before," he said, "for you must comfort our father when I am gone."

His brother gripped his arm. "How strangely you speak!" he said. "Are you going on a journey, then? Why have you not told me of this?"

The knight bowed his head and in plain words he told his brother of the bargain he had made. "It is nothing to grieve over," he said. "Seven years will soon be gone, and then I will return to you. The lord of the Shadow Folk was honest in the cure he gave me, and so I have reason to hope that he will keep the rest of his bargain as faithfully."

His brother looked at him with dismay. "Do you not know?" he said. "Time does not pass in the other world as it does here. The tales all say that one who dwells in the shadow realm for a year, or seven years, as it seems to him, returns after a hundred years in our world and finds everyone he knows dead and buried. And you meant to go without telling me of this?" He embraced his older brother fiercely and pressed his face against his shoulder.

The knight was so dismayed for a moment that he could not move or speak. He held his brother gently, remembering the times when they were young and he had comforted him after a nightmare. "I did not know what bargain I was making," he said, "but if I had known, I would still have done the same. Think that I have met my death in a foreign land – that the king has called me to his banners, or that I have met with misfortune in a tourney. You will aid our father with your strength, and rule his folk when he is gone."

"Our father should know of this," said his brother, troubled.

"Nay, brother! As you love me, do not tell him."

"Our father would be rightfully angry with me, if I do not tell him that he is soon to lose a beloved son."

"He will have grief enough afterward," the knight said. "Let him not have grief and anxiety beforehand also, when he has so recently suffered from grave illness. Give me your word that you will not speak of it to him."

His younger brother was reluctant, but at last he agreed to keep silent.

Over the following days and weeks, the count's son waited constantly for the horn-call. As it did not come, he began to hope faintly that it might never come at all, or that he might be left in peace to live out his full span of years; and then he chided himself for a coward. To distract himself, he often took his horse and went riding alone.

As he was returning home one evening, he saw a flash of white through the trees. He rode after it and caught a glimpse of a white doe passing through a glade before she was lost in the shadows, like the moon appearing for a moment from behind a cloud. He was held still by the beauty and wonder of the sight; and by the time he thought to follow, the doe was gone, leaving no traces behind her.

He almost thought he had imagined it; but the next day, he lingered in the forest as night fell, and once again he saw a flash of white through the trees. He spurred his horse to follow. He caught sight of the white doe more clearly this time, and her grace as she ran was like nothing earthly. Swift as his horse was, the white doe was swifter, and at last he had to admit he had lost her. He turned his horse and rode slowly back to the castle.

He found his brother waiting for him there, concerned that he was returning so late. He was reluctant at first to tell the tale, but his brother pressed him, and at last he told the story of following the doe.

"If you see the doe again, do not follow," his brother urged. "It may be the work of an evil enchantress, or the Shadow Folk seeking to ensnare you."

The knight said in turn, "What harm could an enchantress do me, when I am already pledged to the Shadow Folk? Or why should the Shadow Folk seek to ensnare me when I am already bound by my promise? They could have me in their power any time they wished."

"Nevertheless, there is something unnatural in it," his brother said with a troubled expression. "I beg of you, do not follow it."

"I know you speak from love and care of me," the knight said, "and I will consider your words." He could not bring himself to make any stronger pledge. His heart whispered that the white doe was not a sign of evil, and speculating about the mysterious sight had done much to distract him and lift his spirits. He was not willing to forsake his quest so easily.

On the third night, he rode to the wood again alone. He crossed back and forth under the dark shadow of the trees without finding what he sought. At last, as he was on the point of giving up and returning home, he saw a glimmer of white. His heart lifted. He urged his horse forward a few steps and remained motionless while the white doe stepped delicately past him. He followed her then through the wood, not seeking to catch her or harm her, but only curious to see where she might go. More than once he lost sight of her in the darkness of the woods and had to search again; she seemed to leave no trace or footprint behind her.

At last he could no longer find her and turned his horse's head home. But he had not gone far when the doe sped across his path in a burst of speed, close enough that he could hear her panting breath, and behind her came a large grey wolf.

The knight urged his horse swiftly in pursuit of them, hunter and prey alike. Once the wolf seemed about to sink his jaws in the doe's hind leg, and the knight feared she was lost, but she twisted away and won free. Then the knight was upon them. He drew his sword and struck a mighty blow, catching the wolf between the neck and shoulder. The wolf staggered a few steps and fell.

He cautiously dismounted to make sure it was dead, as indeed it was. When he turned again toward the doe, expecting her to have fled, instead a maiden dressed in white stood before him. Jewels shone in her dark hair, and her face was of unearthly beauty. As he gazed at her in amazement, she swayed and sank to her knees.

The knight hurried toward her. "Lady," he said, "did the wolf do you any hurt?"

She raised her head. "His jaws grazed my leg," she said, raising her skirts modestly to show where the wolf's teeth had drawn blood. "But thanks to you, I suffered no lasting harm."

"If you will permit it, lady, I will bind your wound."

She inclined her head. He did as he offered, then sat back on the ground facing her. He could not find the words, somehow, to speak of the strangeness of what he had seen - it would have been discourteous, he thought, to ask her why she ran through the woods as a doe. "Do you live nearby?" he asked instead. "I will bring you to your home."

"It is not needful," she answered, "but I will not refuse."

He offered his hand and drew her to her feet, then set her on his horse. "Is it far to your house?"

"No," she said. "It is not far."

"I did not think anyone lived in these woods, so near to the dwelling of the Shadow Folk."

"Perhaps that is true, but my brother's house is here." She pointed through the trees.

The knight mounted behind her and followed the way she indicated, though he could see no sign of a path. "Is this the way?" he asked more than once, and each time she replied, "It is not far."

At last they rode through a screen of trees, and suddenly the knight knew the place. Perhaps some enchantment that had veiled his eyes was now lifted, or perhaps it was the moonlight making familiar paths strange. It was the place of twisted stones, marking the rim of the valley where he had made his bargain with the Shadow Folk. "This is your brother's house, lady?"

"It is," she said. "My brother is waiting below." She held up her arm, and through the trees a white falcon came swooping down to light upon her hand, the talons closing gently so as not to tear her flesh. And in the moonlight, the falcon's sleek feathers shone as brightly as when he saw her on the Shadow hunter's wrist, with the tail and wingtips as red as fresh blood.

She sprang lightly from the horse, seeming not much hindered by her injury. The falcon spread her wings for balance but did not stir from the lady's wrist. The light shifted, and in the valley that had been empty, a house now stood, with arched door and high towers. The hunter of the Shadow Folk stood before the door, his looks stern. The lady made her way down to him and spoke some words which the knight could not hear. The hunter caught her shoulders and drew her to him, and the knight smiled in spite of himself to see a lord of the shadow realm with an expression much like his when he reprimanded his own younger brother for some dangerous adventure.

The lady spoke again and gestured up the slope toward him. The hunter turned his gaze upward and the knight felt himself transfixed by that bright glance. The hunter inclined his head with grave courtesy. Then he took his sister by the hand and led her toward the house. The moonlight which shone around the door of the house grew very bright, so that the knight had to look away. He felt more than saw the moonlit door close. When he looked back again, the valley stood smooth and empty, and the space below the twisted stones held only grass.

He did not know how long he stared. His horse shook his head, jingling his harness, and that broke his trance. In silence, he turned his horse's head and rode slowly homeward.

Though he went often to the forest by night and more than once even dared ride as far as the rim of the valley, he did not see the white doe, and no house with a moonlit door appeared between the stones - only long lush grass, where his horse was more than willing to graze if the knight let his thoughts wander.

Perhaps a fortnight later, the count and his sons with their folk were sitting at meat. The knight had just poured himself a cup of wine and was raising it to his lips, when a horn-call rang out in the distance, high and eerie. At once he knew that he could not have mistaken this call for anything else. He set the cup down again untasted. The knight looked around him, but saw only folk laughing and feasting as before, seeming to notice nothing amiss. He wondered for a moment if he had imagined the call. Since he had spent so much time awaiting it, did his mind now conjure phantoms to trick him?

The call came again, but closer. The echoes died away mournfully. The knight rose to his feet.

His brother looked at him with concern. "What is it, brother? You are pale."

"Did you not hear the horn?"

"Truly, I heard nothing."

"Did you hear a horn blowing?" the knight asked more urgently of those around him.

"I heard nothing, lord," said an old squire. "Sit down again, and feast with your people."

"Is something amiss, my son?" the count asked.

And a third time the call came, this time as loud as if the one who sounded it stood outside in the courtyard. Yet he knew that if he looked outside, there would be nothing to be seen. He could tell from looking at the faces of those around him that they could not hear it. It was like something in a dream; yet suddenly it seemed to him as if all the bright and laughing folk within, the old castle itself, were nothing more than a dream, and the only real thing was the Shadow keep in the forest where the horn-call summoned him.

"I am summoned," he said, and turned to go.

His brother sprang to his feet in alarm. "Do not go, my brother! None of us heard it. It is nothing."

"I heard the call, because it is for me. I have pledged my knightly word, and I must go." And though his brother wished to stay him, he went swiftly from the hall.

"My son! Where are you going?" When he received no answer, the count turned to his younger son. "Why does your brother go from us so swiftly?" he asked. "And where does he go? I know he has been troubled of late, but I thought I would wait until he wished to speak of it."

"Ask me nothing!" his younger son said fiercely. "Ask me nothing, for I will not speak of it. He may yet return."

"Does he go to meet some danger?" the count asked in alarm.

But his younger son steadfastly refused to speak. "He goes where his plighted word calls him. But he has returned to us before out of great peril. If he has not returned in three days, you may ask me then." And with this the count was forced to be content.

The knight rode off into the darkening forest, journeying under the shadow of the trees along the way that led to the valley of the Shadow Folk. At first he rode wildly, urging his horse along; but then he thought that it might be the last time he came this way, and he slackened his speed. He went neither swiftly nor slowly, letting his horse take its own pace.

As he approached the eaves of the forest, he heard a cheerful whistling and saw a woodcutter on his way home for the night, bearing his axe over his shoulder.

"Greetings, my lord," the woodcutter called to him. "It is growing dark. Why do you ride alone through the wood?"

"I ride to keep an appointed meeting," the knight said.

The woodcutter shook his head. "The forest is an unchancy place," he said. "It is not good to travel there after dark, and I fear your errand may be unlucky. Will you not wait until daylight?"

"I would gladly wait for daylight, but my errand is one which will not wait."

The woodcutter scratched his head. "It is said the Shadow Folk haunt this forest. And they are tricky to meet with at the best of times. Please, my lord, go back."

"I thank you for your counsel," the knight said. "But I have pledged my word."

And when the woodcutter saw that he would not be turned aside from his path, he bowed and said, "Then good fortune attend you, lord."

The woodcutter went on his way, and the knight rode onward. He had not travelled far when he heard a man's voice calling through the wood. He rode to see what the matter was, and there was a shepherd who dwelt near the forest. He held a lit lantern in his hand and he was looking about him anxiously. When he saw the knight, he bowed and took off his cap.

"Greetings, my lord," the shepherd said. "The hour is late, and the night is growing cold. Why do you ride alone through the wood?"

"I have made a certain promise," the knight said, "and I go to fulfil it."

The shepherd twisted his cap between his hands. "If you could spare a few moments from your errand, my lord—My son is lost in the forest, and that is why I am here so late. Otherwise, I would never come here after dark, so near to the Shadow Folk. It is said they steal children, and I am afraid—"

The knight pitied the man's distress. Surely, he thought, there was still time before he must appear at the house of the Shadow Folk. "I will help you search," he said.

He dismounted and let his horse graze, while he went back and forth through the wood while the shepherd called for his son. The knight was the first to spot the boy, wrapped in his father's old coat and curled up at the foot of a great oak tree, and he touched the shepherd's arm. The shepherd let out an exclamation and ran to his son's side. The boy was fast asleep but unharmed. He opened his eyes and blinked sleepily at his father.

"Why do you make me worry so, my son?" the shepherd scolded. "What were you doing in the forest all this time?"

The boy hung his head. "I am sorry, Father. I fell asleep, and then I could not find my way back in the darkness."

The shepherd embraced his son. "Come home now," he said. "Your mother has been waiting for you."

The knight was glad at heart to see their reunion and to know the boy would reach home safely; that his father and mother need not mourn as his own father would soon mourn for him. "Since you have found your son," he said, "I must be on my way."

The shepherd thanked him many times for his help in the search and made the boy thank him as well. "But where is your way, my lord?" he asked. "Surely you are not going on into the forest, so late at night?"

"I must," the knight said.

The boy gasped and the shepherd frowned. "It is said the Shadow Folk live in that valley. Turn back, lord, before some harm befalls you."

"I thank you for your counsel," the knight said. "But I have pledged my word and I must go onward." When the shepherd saw that he would not be persuaded, he went off with his son, though he looked back often and shook his head.

The knight found his horse, which was placidly cropping mouthfuls of grass, and rode further into the forest. He had not ridden far when he saw an old woman, making her painful way along the forest path, bent nearly double under a pile of sticks and brushwood. He pitied her burden, and it seemed to him there was still time before moonrise. He halted his horse to speak with her.

The old woman looked up, grimaced at him, and shook her head. "It is already late," she said. "It is already cold. Why do you ride alone through the wood?"

"I am going whither I am bidden," the knight said. "But surely that is a heavy burden for you."

"It is, it is. I am not so spry as once I was. I meant to be home before night fell, but here I am still in the wood, with a distance yet to go."

"Let me help you," the knight said. "My horse will make little of such a burden. He can easily bear you and your bundle as well."

"Oh no," she protested, drawing back. "I can never ride so large a creature! I would risk breaking all my old bones."

"Let me at least take your bundle," the knight said. "That way you will reach home more quickly."

She bobbed her head. "Thank you, my lord. You have a kind heart."

The knight dismounted and lifted the bundle of sticks onto the back of his horse, which had surely never borne such a load, but accepted it calmly enough. He matched his strides to the slow pace of the old woman and took the path she directed.

"But where were you riding?" the old woman asked him. "The Shadow Folk haunt these woods. You were near to their valley. That is an ill place to seek out for any man born of woman. Surely you were not going there?"

"I was," the knight said, "and I am. Once I have seen you home, I must return there. I have given my promise."

"No, no, my lord," she said in distress. "You must not go there. Never mind your promise. A promise made to the Shadow Folk is not like a promise given to man or woman. Once you are away from here in bright daylight, they cannot pursue you. Do not go there!"

"I have pledged my word," the knight said, "and I must not falter."

The old woman did not argue, but she muttered and grumbled to herself under her breath about his foolishness. The knight thought it more courteous not to heed her. After some time, he asked, "But is your house nearby?"

"It is here," said the old woman. She pointed through the trees at a rickety hut with a scraggly thatch roof.

The knight took the bundle of brushwood from his horse's back and set it down. When he looked up again, both the hut and the old woman were gone. Instead, the Shadow lord's sister stood before him in her jewels and her gown of white.

The knight started. She smiled at his surprise. "I was the woodcutter," she said, "and the shepherd seeking his child, as well as the old woman with her burden."

"And the shepherd's child?" the knight asked quickly, for he remembered the tales of the Shadow Folk stealing children.

"An illusion only," she answered calmly, "woven of moonbeams and magic. I wished to test your heart – to be certain that your kindness to me was no accident, and to see whether you would be daunted and turn back - and so I came to meet you these three times. But also to thank you, since I think we will not meet again."

The knight stood in silence for a few moments. "We will not meet in the shadow realm?" he asked her sorrowfully. The thought of seeing the lady again, perhaps of aiding her in some way as he served her brother, had been one of his consolations for his grievous fate.

She tilted her head to one side and regarded him with bright eyes like a bird's. "The shadow realm has laws which cannot be changed," she said, "even by its lord. The bargain you made binds my brother as much as it does you."

The knight bowed his head, accepting his fate.

"Do you remember your promise?" she continued.

"I remember it well, lady. I must offer myself to the lord your brother, to serve him for seven years in the shadow realm – though I know it will be far longer than that in the world of men."

"That is well," she said. She made him a courtesy and turned away, vanishing between one breath and the next. The knight remounted his horse and rode onward with a heavy heart.

He arrived at the rim of the valley and looked down. Only silence greeted him; yet he could feel a sense of watchfulness. Among the trees below, something was waiting. He dismounted and led his horse down the rocky slope.

When he came to the foot of the hill, he looked up and saw the house appear before him. This time it seemed long-deserted; the tower was crumbling and the bright windows were veiled with ivy. Again he had the certainty that there were folk within the house, watching and listening for what he would do next. He stood a moment and stroked his horse's nose. "You will return to them," he said, "and they will know I have gone to my fate." His horse snorted and calmly lowered his head to graze.

The knight looked about him once more, at the earthly trees and sky he might not see again for a long time, and then he went forward. The trees overhead and the hanging vines cast dappled shadows over the house, but the moonlight gathered very brightly around the door. He struck the door firmly with his fist. "Is there anybody there?"

No answer from within the house; but a fluttering of wings from the tower made him look up. It was a snow-white falcon that glided from some perch in the tower, though the shades of night turned the red tail and wingtips to black. The bird circled once above his head and landed on a branch of an old oak tree, where she sat facing him. The knight inclined his head. Though the Shadow lord's falcon might still be only a falcon, there was no harm in courtesy. The bird watched him with bright eyes.

The knight turned again to the moonlit door. Again, he knocked. "Is there anybody there?" he called.

Again, silence. He knew – he could feel that there were listeners within, that they heard him. For a moment he stood perplexed. There was no sound but his horse cropping the grass of the forest floor.

The falcon launched herself from the branch and vanished once more into the tower with a clap of white wings.

Suddenly, in a flash of brilliant hope, he understood the gift he had been given. The lord too must obey the laws of the shadow realm – so his sister had said. They had not the power to release him if he did not keep his part of the bargain, to offer his service. He must offer, but they were not bound to accept.

He struck once more on the door. "Tell them I came," he said, "and no one answered. That I kept my word." Only silence answered him.

Still half-disbelieving, he turned away and sought his horse. He mounted and rode away, his horse's hoof-beats sounding very loud in the echoing silence. As he reached the crest of the hill, he felt something behind him like a door closing. He rode onward through that dark wood and reached his father's castle once more as the first rays of dawn were lighting the sky.

Notes:

This story has a mix of influences including fairy tales, the Mabinogion, Arthurian legend, German art songs, Child ballads, and J.R.R. Tolkien, but here are a few specific things I can pick out:

The white hound with red ears is based on Arawn's hounds in the Mabinogion.

The ominous horn call as a summons to fulfill a pledge is from Verdi's opera Ernani.

"It is already late, it is already cold. Why do you ride alone through the wood?" (Es ist schon spät, es ist schon kalt, / was reitst du einsam durch den Wald?") are the opening lines of the poem "Waldesgespräch" by Joseph Freiherr von Eichendorff (as set by Robert Schumann), where they are spoken by a traveller to a woman who turns out to be the witch Lorelei.