What Amy hadn't realized was the Sherlock had been watching her and the Doctor from the window up high. Despite being able to hear their conversation, the detective guessed the nature of it going by their expressions and actions. When he saw them leave, making off up Baker Street, he became increasingly curious. Amy knew the man who he had once seen at a university lecture, the man who still looked exactly the same over a decade later, and the previous events that had occurred some months earlier, plus the mystery behind his red-headed flat mate were starting to tug their way into his interests.

And so he put on his coat, circled his scarf around his neck, then left the flat. Yes, he was working on a new case and interruptions were more often than not unwelcome, but this one was important. Figuring out Amy was more important. He liked to know about the people he knew. Not knowing was something he hated.

The chill in the night air greeted him but it wasn't enough to make his breath visible. Quickly, he walked, until he could faintly see the two figures of Amy and the Doctor in the distance. He thought it strange how he hadn't been invited to come. Mind you, the Doctor did say he was taking Amy back to Leadworth, right?

There was no Leadworth in London.

The minutes ticked by and Sherlock continued walking, passing shops and drunken teenagers and cab after cab after cab, his attention focused only on the Doctor and Amy. Up ahead was London Bridge, it's silhouette bold and black against a dark blue canvas. The more he got closer, the less black it looked and the more defined it became. The Doctor and Amy turned, carried on, straight towards the Tower of London. The last time Sherlock had been there Moriarty had attempted to steal the Crown Jewels.

Why were the Doctor and Amy heading towards the Tower of London?

He stopped and watched as they were greeted by a blonde woman and were led off into the tower. He glided closer to see where exactly they were entering the tower from. It came to his attention that there were military vehicles parked outside, and some guards dressed in camouflage and red head wear in the dim streetlight. He was aware of the Tower of London occasionally being used for military purposes. The question was, what reason did Amy and the Doctor have to be there?

He knew he wouldn't be able to get past without authorization. Annoyingly, he didn't have the ID card he had pick pocketed from Mycroft on him. Since when did that stop him?

He had broken in. He had broken into the Tower of London. He had broken into a temporary military base... It hadn't taken Sherlock that long but it hadn't been easy. He'd been out of practice for some time.

Once inside, he did his best to avoid getting caught, and started searching for the Doctor and Amy. Where had they gone to? The Tower was big, there were so many places they could be, did he have time to search them all? There were two guards that he followed, sticking to the shadows so he wasn't seen. Stealth. He liked stealth occasionally. The guards weren't talking, just walking, and when they turned a sharp corner Sherlock stopped. With his back against the stone wall, he peered gradually around the corner and watched them open a door, disappearing behind it once it had shut. After seeing if anyone else was around, Sherlock made for the door.

It was a stair case, made of metal encased in darkness and drafty walls. With no hesitation he went down it, wondering what he would find at the bottom. The last step came and his hands went forward, feeling another door. He tried to open it but it was firmly locked. He wished there was a light so he could bloody see! His hand rested on something square in shape, sticking out from the wall, smooth on the surface, cool to the touch. Tracing his fingers down the side he found a join and he prized it open. A bright blue screen with a touch pad of numbers appeared. The security lock. No problem, thought Sherlock as he examined it, trying to find a way to work out the code. There were several ways. Looking for the fingerprints was easy, it was just working out which order they were in. The first number was clearly a three, and the last was six, but the others in between -

Someone was coming. Hastily, he dived away from the door and hid himself underneath the stairs, a cramped space in which he was sure he would suffocate in. The footsteps stopped and he saw someone at the door. He shifted, the keypad coming into view and he managed to see the code the person tapped in. He wasn't anticipating that to happen but it worked in his favor. He saw light from another room as the person slipped inside. Once the door had closed, Sherlock went back to the door, tapped in the code and opened the door.

It wasn't a room, it was a basement. It wasn't even a basement... It was huge. Blue and white lights illuminated the area that was filled with control stations, glass cells and crates. He didn't stop and stare - that would be too conspicuous. He walked inside, avoiding people, and scanned around. There were vaults to his left, and tabletops strewn with weird artifacts with unfamiliar markings and flashing lights; but he was more focused on finding the Doctor and Amy. Not that he wasn't interested in finding out what was going underneath the Tower of London. He would love to know. It could be information that he may find useful in the future.

Voices to his right reached his ears. That familiar Scottish lilt that was Amy's. Yes! Now he would be able to see what she was up to, possibly find out what she had been hiding from him... There was a control station next to him. He took the opportunity to sit at it without being suspicious and listen...

"...not a shapeshifter, Amy. Well, it is, but it's not, but it kind of is. This species is particular. They can't change their form unless the form they want to use is dead. They feed off energy from any life form they like, and they don't care if they end up killing them in the process."

"That's horrible."

"It's how they survived."

"Survived?"

"The race is dead now. All of them. No, not all of them. He's the only one left. The Council of Ordo decreed that the race be incinerated along with the entire planet of Vietica. I wasn't even alive when that happened. It's not their fault they need energy from other life forms to survive."

"Where's he been then?"

"He's been locked up in the Ordo Prison for centuries. I cant't blame him for wanting to escape. But when he did, he stole the Diamond of Kadia, and believe me, Amy, if I hadn't have stopped him one of the biggest empires in the universe wouldn't be here now. That's why he's been on Earth. He traced me here to try and reclaim his 'prize', only he's old and his navigation is extremely bad..."

"We can't detain him here for much longer, Doctor," said another female voice Sherlock did not recognize.

"It's fine. I'll take him back to the Ordo Prison using the TARDIS..."

Sherlock frowned. The Ordo Prison? Incineration of an entire planet? The TARDIS? What was this jibberish? Had he suddenly been transported into one of those ridiculous sci-fi films John made him watch once? For once, Sherlock Holmes didn't quite understand what was going on. But it was real. All of this was real. He didn't have fantasies. Even if he did, they would not be like this! They were talking of aliens. Sherlock had been there when Alexander Harvey had practically confessed to being a shapeshifter, yet he had still been very skeptical. He could only believe the evidence of his own eyes. Until he actually saw this 'shapeshifter' do whatever it is they do, he would remain skeptical. And as for Amy -

Someone tapped him on the shoulder and he turned abruptly, coming face to face with a hard-faced old man. "Who are you?"

Sherlock realized he had been outed, so he put on a childish smile. "I'm sorry, I must have taken a wrong turn."

The man was angry and reached for a walkie-talkie. "Call security. We have an intruder."

With that, Sherlock flew from the chair with lightning speed and fled for the door, just as the sound of high-pitched alarms started blaring and red lights flashing from every corner of the building. Luckily, the door opened without a code from this side and he went through it rapidly, heading up the stairs. There was nothing like running from trouble to stimulate the brain. He was being chased by three guards. He was much quicker than them, light on his feet, his coat swooshing behind him. Down the corridor he went. For a while he thought he was going to escape scot free. He was almost near the entrance from which he broke in from. He could see it up ahead in the dim light. Almost there - Only two guards came from the other way, and stopped him in his tracks.

They stood in front of him, firmly holding guns. "Where do you think you're going?"

"I was just -"

"Cuff him." On went the handcuffs as a guard from behind slammed him against the stone wall, grazing his cheek. Then he was being pushed forwards, forced along the corridor as he was escorted from the building.