Northern Germany, Earth, c. 150 000 000 BCE

Dawn had barely broken, but Helen Cutter was already on the move. Oversleeping could very possibly equal death when one's bed was in late-Jurassic Europe, and Helen had never been one for lounging around for half the morning. As the first rays of the sun sprinkled the tips of the conifers in their golden glow, Helen was already checking the third of a dozen snares she'd set up around her camp on the edge of the forest. The process took little over half an hour, but every one of them turned up empty.

Helen sat back on a rocky outcropping and pulled her water bottle from her backpack, taking a long drink as she wiped the sweat from her forehead. It was only her fourth day in the forest, and already the few mammals that were around had learned to stay away. She marvelled at their keen senses even as her stomach grumbled. They were so much more alert than the mammals of her present... especially the humans that had the audacity to consider themselves the top of the food chain.

With a short sigh, Helen stood up and tucked her water bottle away. It was close to empty, so she began to make her way down to the lake to refill it. Animals came to drink from it regularly, but they were mostly sauropods and iguanodons, or else turkey-sized theropods. Most of the bigger dinosaurs were still sluggish this early in the morning, so Helen had no trouble reaching the lake. Once she'd filled the bottle, though, she decided it was time to move on. The Jurassic period was interesting enough, but she'd spent a lot of time in it lately, and she was craving a new adventure. First, though, she wanted breakfast.

There was a flock of Archaeopteryx that made their home on the far side of the lake. Birds weren't as hard to prepare as mammals, and Helen had patience and excellent hand-eye coordination. As she walked around the lake towards the nest, she fished her rope sling out and picked up several good-sized rocks. She loaded the sling and began to twirl it lazily by her side, her ears pricked for any sign of danger, always glancing left and right as she walked.

Her eyes were very good. She spotted the flock nesting in their usual tree, not too far up from the ground – Archaeopteryx were only capable of weak flight, something Helen planned to use to her advantage. Still she was looking all around, left and right for enemies, down to watch her step, up to watch her prey. She was ten yards away, then five. She moved very slowly, breathing quietly and evenly through her nose, the sling spinning rapidly and silently by her side. In her left hand she drew her knife.

One of the Archaeopteryx lifted its head, its mouth opening slightly to reveal its sharp teeth. It spread its wings and croaked an alarm. Instantly, Helen's arm was up and the rock shot from the sling, flying at high speed through the trees, towards the bird. It caught it on the wing – not quite what Helen had been aiming for, but with enough force to knock the bird from its perch. Helen was already running, transferring her knife to her right hand. As the Archaeopteryx righted itself and prepared to take flight, she threw the knife, this time with perfect accuracy. The rest of the flock screeched and fled, but she had already made her kill.

After plucking, cooking and eating the Archaeopteryx, Helen set off to find an anomaly. By midday, though, she had grown tired of searching. She hated using the detector – she kept it for emergencies only – but it was an unseasonably warm day and she'd been wandering through the forest for hours. The anomaly she'd come through four days ago had disappeared long ago, and she had no way of knowing how far away the next one was. Plus, she had the taste of feathers in her mouth. And she would kill for a shower.

Helen sighed and paused, shrugging her backpack off her shoulders, when she heard a rustle from one of the trees up ahead. Another flock of Archaeopteryx had taken flight, screeching concerned calls. Helen frowned and swung her backpack back on, making her way slowly over to the site, one hand, as always, on her knife.

In a small clearing that opened out a little further on, an anomaly had appeared. It shimmered gently in the air before her, oddly silent; there couldn't have been much going on on the other side. Helen grinned and checked the clearing briefly for any sign of predators before approaching the anomaly. With her knife gripped tightly in her right hand, she waved goodbye to the late Jurassic and stepped through.

Stormcage Containment Facility, Stormcage, 5133 CE

Perhaps it was early morning, or perhaps it was late at night. The ceaseless rain and sterile prison atmosphere made it difficult to tell at times. River Song wasn't terribly bothered; she didn't take knowing what year it was for granted, let alone what time of day. The bench on which she sat was cold and hard and uncomfortable, but she'd grown used to it by now. She was leafing idly through her TARDIS diary. It was a little frayed around the edges now, a little faded, but it contained the most important memories of her life.

Footsteps sounded in the corridor outside and River looked up hopefully, but it was only a guard patrolling past her door. He didn't look into the cell as he walked, and River slumped against the wall, closing the diary. She didn't know what time of day it was, but she knew it had been weeks since the Doctor had last sprung her from her cell to take her on an adventure. She was mind-numbingly bored. It was, River decided, past time she concocted her own escape plan.

The moment the thought crossed her mind, a rip in the fabric of space-time appeared in the centre of her cell.

River blinked, standing up slowly from her bench, the diary clasped tightly in her hands. She stared at the shimmering portal, walked in a slow circle around it, reached out to touch it. It seemed to pass through her, and at the same time, she passed right through it. There was a soft whispering emanating from it, and she instinctively knew that it led to somewhere very, very far away. "Oh, Doctor," she said quietly, "what have you done this time?"

Just as she completed her circle of the portal, someone ran through it.

Human, female, perhaps thirty or forty years of age, she was dressed in clothes that looked very well-worn and not a little ragged. She had a backpack over her shoulders and a bandanna around her neck. She also, River noticed, had a knife in her hand. River took a slow step backwards, and the woman turned to face her.

"Who are you?" Her voice was low and soft.

River raised an eyebrow. "I would think it ought to be me asking the questions, seeing as it's you intruding upon my cell."

"A cell?" The woman looked around. "Where is this? What year is it?"

"Well, well," River murmured. "It seems I'm not the only one who loses track occasionally. Did the Doctor send you?"

"Who?" The confusion on her face was clear to see. River slipped the diary inside her jacket.

"Put the knife down," she instructed. The woman obeyed, holding it by her side. Her gaze darted all around, to the walls and ceiling and floor of the cell, to River, to the bars that separated them from the outside, to the shimmering time portal, to River again. "My name is Dr River Song," River continued. "I'm an archaeologist... and a convicted murderess." She grinned. "This is the Stormcage Containment Facility. I'm very curious as to how you made it in here."

"Helen Cutter," was the terse response. She sheathed her knife. "Who did you kill?"

"The greatest man in the universe," River replied. "Otherwise known as my husband." This time it was Helen's turn to raise an eyebrow. "Long story," River said. "It's approximately 5133 in Earth years, if I remember rightly. When are you from?"

"Late Jurassic," Helen replied. "Actually, I should be getting back. Prison isn't really my thing."

"Nor mine," River said quickly. "You should take me with you."

Helen stared at her.

River gave a short laugh and folded her arms. "I'm an archaeologist, remember? I'm not going to be scared of a few dinosaurs. Quite frankly, Helen Cutter, I'm going absolutely crazy locked up in here. Disappearing through a portal in time is much easier than breaking out. I'd be interested to know exactly how one of these... things comes into existence, too. As would the Doctor, I'm sure."

"They're called anomalies," Helen said slowly.

"Is that so? How interesting. I've never seen one before – and believe me, I have a fair amount of experience at travelling through time."

"How, if not through an anomaly?"

River simply smiled. "I have my ways," she replied enigmatically. "I could show you... if you'd take me along."

Helen considered her for a long moment. Eventually, she drew her knife again. River tensed up, and Helen let out a barking laugh. "Relax, Dr Song. Just a precaution." She turned her back on the cell and faced the anomaly, then glanced over her shoulder. "You coming?"

"Oh yes." River blew her beloved cell a kiss, and followed Helen through the portal in time.