John arrived home from the clinic with heavy bags of shopping in his hands. He entered the living room and stopped in surprise when he saw Sherlock and Mycroft sat opposite each other in silence.

"Did you bring milk?" Sherlock asked, getting to his feet and making his way over to John.

"Yes." John replied, retrieving the bottle of milk from his shopping bags. He leaned around Sherlock to look at Mycroft, who was sat perfectly still with his eyes closed. "Is Mycroft okay?" he asked his flatmate.

"He's fine. He's doing some research for me." Sherlock replied, waving his hand dismissively and walking into the kitchen with the milk.

"Right..." John muttered under his breath, carrying the shopping bags into the kitchen. He put all of the shopping away before he went back into the living room. He stood awkwardly for a few moments, taking the opportunity to observe Mycroft whilst the man was distracted.

"Stop looking at my brother, John." Sherlock said as he entered the living room and sat down in his chair again.

"Is he in his...mind palace...?" John asked as he sat down at the desk behind Sherlock's chair.

Sherlock scoffed, "Mycroft doesn't have a mind palace. He's boring. He just has a mind map." he said.

John laughed a little, "You have mind palace rivalry?" he joked.

"Of course not, John. Mine is much better than his. There is no rivalry." Sherlock replied, no longer joking.

"How can you be so sure? You've never seen his mind map." John said.

"It's like a rabbit warren in there. I don't know how he finds anything." Sherlock muttered.

"What? How do you know?" John asked in confusion.

"I hypnotized him, obviously. It was an experiment. It was just once, so I don't think he even remembers it." Sherlock replied with a shrug.

"But that doesn't make any sense!" John exclaimed, "If a mind palace is imaginary then how can you see what Mycroft's looks like?"

"One again, John, you astound me with your mental prowess." Sherlock drawled sarcastically, "I had him describe it to me. I would have asked him to draw it, but Mycroft has always been atrocious at art."

John rolled his eyes, "Of course. Obvious." he muttered.

There was silence in the flat for a few moments as both flatmates naturally paused in their conversation.

"Forgive me for being obvious, but if you can just hypnotize him, why do you need him to search through his own mind for information?" John asked.

Sherlock scoffed, "Mycroft would never consent to hypnotism." he said, "Also, his answers would most probably be carefully constructed lies. He has built his mind to withstand interrogation. I doubt even the most sophisticated torturer could get to the truth."

"Yet you managed to hypnotize him?" John asked.

"That was a long time ago, when we were both much younger. I was practicing hypnotism as part of my Psychology A-Level and Mycroft was still working his way up to the top. He didn't need to have strong mental barriers until he reached 30." Sherlock explained.

"Mummy did teach you it was rude to talk about someone behind their back, Sherlock." Mycroft's calm and composed voice said as his eyes fluttered open.

"We're talking about you to your face, Mycroft. You just weren't listening." Sherlock replied.

"Anyway, brother dear, the agent's name was Alexander Hamilton." Mycroft said, "He went rogue during a mission some 20 years ago. He managed to avoid capture through moving countries and changing his name regularly. He was impressive, but he is dead."

"How can you be so sure?" Sherlock asked, writing down the name on his case whiteboard.

"I shot him myself." Mycroft replied, his voice cold and sharp.

"And you're absolutely sure it was him?" Sherlock asked, scrutinizing his brother.

"It was him." Mycroft replied without hesitation.

"Very well, brother, you may leave." Sherlock said, his attention focused on his whiteboard.

"John, I would appreciate it if you didn't repeat what my brother has told you. Some secrets are best kept as secrets." Mycroft said as he got to his feet, swinging his umbrella slightly.