Chapter 1 – The Base

Sherlock and John met Lestrade in front of an old, and now empty, warehouse far outside the outer ring of London. The detective inspector filled the two men in on the situation, explaining that this was one of Jim Moriarty's former bases, a place where he recruited men and had kept his weapons. Even though they had been too late to stop Moriarty from emptying the base and move its content to a new one, it was still worth a lot to look around.

"Perhaps you can deduce his new location, Sherlock," Greg concluded and started to walk the two men into the building. "As you can see, the move was quite organised. Not one spot seems to reveal the warehouse's last use."

Sherlock nodded and looked around as well. Unfortunately, Lestrade seemed to be right. There wasn't a scratch on the walls or floor, and nothing was left behind. After a ten minute walk through the entire building, he met Lestrade back outside.

"Nothing to be found, except for one thing," Sherlock said. John frowned and looked at his flatmate.

"One thing? We just went through the entire building and all you did, was saying 'no, no, no' over and over again. What one thing did I miss then?"

Sherlock grinned and looked at his shorter friend.

"You miss a lot more than you think, John. You see, but you do not observe."

"Well, I can observe right now that you are an arrog–"

"Guys, please. Can we get to the point? What did we miss, Sherlock?"

Sherlock sighed. He was just started to get on fire with this game of 'minor' insults. He looked up at Lestrade again.

"Well, we've been downstairs twice now and only one time upstairs. I can guarantee you that the upstairs area is empty and completely useless to this investigation. Downstairs, however, the police – and John – has missed something that can possibly make the entire investigation as simple as –"

"And what did we miss?" asked Lestrade again, rather impatient and not in the mood for Sherlock to take his time to try to show off his great intellectual skills.

"A door," Sherlock stated and then put on a smug grin.

"A door?" asked Lestrade, to which Sherlock nodded in confirmation.

"A door? Sherlock, the building is made of thick concrete and inside there are no more doors. You and I both saw that," said John.

"No, John," Sherlock responded, "you saw that, but I observed something completely different. Well, not completely, as there is only one door, but I did observe something different from what you saw. You missed the clue by looking."

"Fine, fine. I got it," said John, slightly annoyed.

"Good, now that that's settled, show us the door, Sherlock," said Greg, after he had gathered ten men with guns. Sherlock walked them to the 'door', but none of the men actually saw it. They stared at the concrete wall, and for a moment, Lestrade thought that Sherlock had lost his magic touch.

"A rock," said Sherlock.

"A what?" mumbled John.

"A rock. I need a rock. Bring me one."

John looked at the police officers, but none of them attempted to move, and so he sighed and fetched Sherlock a rock from outside himself.

"Is this one okay?"

"Perfect, thank you," Sherlock said and walked to the wall. "Gentlemen, I can observe that you all are looking at this wall. However, looking will bring you nowhere. You must observe, meaning you must both watch, listen, connect, dissect, process, and whatsoever, every moment and all at the same time. I can understand that just by looking, none of you know what I know." He walked a few times past the wall, emphasising the pressure on his heels so that the sound of it echoed through the room. "Now, I want you to close your eyes and listen to the sound of my shoes. When you hear a change in sound, click with your tongue. Ready? Good." The men hesitated for a moment, but Greg told them to do what Sherlock asked from them, and so they did. Sherlock walked past the wall, and when most men clicked their tongues, he stopped. "Open your eyes," Sherlock said. "This is where the sound changed. Now listen to this." Sherlock tapped the rock loudly against the wall and went back the way he walked. The sound of the rock hitting the wall also changed. He turned to Lestrade. "The area behind this wall is a hollow one. This wall is thinner than the other, outer wall."

Lestrade came forward and touched the wall.

"Alright, but how could we miss another room? We should have been able to notice it from the outside."

Sherlock shook his head.

"The room is under the hill that meets the wall outside. But that would mean that the room is small, way too small for a human to walk in. Therefore, this room goes deeper into the ground. That is all I can tell you. Considering the side of the hill, the room might be rather small. Then again, it might become bigger when it gets further underground."

"Good work, Sherlock, I must give you that," Lestrade said. "But where is the door?"

"Hm? Ah, do you have a pen and a ruler?"

Greg shook his head.

"I've got a… roll of police tape and a marker."

"That'll do fine."

Two police officers brought the two items, and held a piece of the police tape tightly against the wall. Sherlock took the marker and drew a straight line along it. Then the police tape was removed, and Greg managed to point out where the door was, by looking at the line from a few metres away, and seeing the slight inconsistency in the straightness.

"There. That's the door. But how…"

Sherlock started to hit the rock in several places. First along the edges of the door, easily chopping away the newest layer of concrete, as it was placed in a rush and thus had much air in it, and then where he thought the handle would be. He found it after several minutes of chopping away.

"Now," he said, dropping the rock and patting the dust off his jacket. "All we need is some manpower to open it."

John stepped forward.

"I'll do it," he said, grabbing the handle and holding his gun in his other hand. The police automatically got into position, and Sherlock and Greg took a few steps back. After a few times of pushing and pulling, the thick concrete door opened slowly. There was a rather dark room ahead, but John could see a faint green light, and stairs that went down among two edges of the square room. It was a deep area, and at the ceiling it was small, but downstairs it was quite large. John held his gun tight as he set foot on the stairs, made of iron. Just as he thought the room was empty, he saw a person among the many machines and laboratory tables. It was only a girl, or a young woman. His footstep on the iron had echoed through the room and she was now looking at him. John instantly stepped back, and tripped, and then…

Bang!

A gunshot.