It had been almost two days, and so far Sherlock was having no luck in locating John. Some of his homeless people had seen a black car drive into Mike's neighborhood the night John was captured, and had tracked it for a while, but had lost it in the traffic around Westminster. Nobody else had been able to find it. The irate detective paced through the streets in apoplectic frustration. He even went back to Baker Street, in case Brother Dear had been sneaky enough to put him back there, but only found that the skunk smell had not yet dissipated.
But the afternoon of the second day, Sherlock had some news. A homeless girl who was not a regular part of his network, and so did not get the message of his need for information until today, thought she had seen a car fitting the description of the one that had taken John drive up to the Diogenes Club, and two men carry someone else inside, but figured it was just a couple of blokes taking their drunk buddy home, and so had thought nothing of it. It was a testament to how much both having John in his life and playing dead for 2 years had changed him that Sherlock did not either start swearing a blue streak or pour a torrent of abuse on the girl's intelligence. All he did instead was offer a pound, and a "thank you" through gritted teeth, before sweeping off toward the club.
He waited until nightfall before breaking in. It was relatively easy, as long as he kept one step ahead of the CCTV cameras. Some club members were still there, snoring under their newspapers. Sherlock barely gave them a glance; if he knew Mycroft like he thought he did, John would not be in the main part of the building. No, he'd be kept down below somewhere. So, casually disguised in the uniform of the people who worked here, Sherlock Holmes descended the stairs into the depths of the club, where the kitchen and servants' space was. At first he had no luck; the rooms he checked, on the pretense of cleaning if anyone asked, were empty of John, and there was no evidence he had been in any of them. But he found success when he checked the lockers belonging to the workers: in one of them, he found John's jumper and shoes, all of which had been neatly cleaned and washed. So he was somewhere on the premises. With a smile of satisfaction, Sherlock removed the items and closed the locker, turning the combination back to zero. And promptly got the second stroke of luck of the day. As soon as the spinner was back at zero, the wall behind him slid aside, revealing a most peculiar door. It was made of metal, and even though he could see hinges, there was no apparent knob. Also, the middle had what looked like a circle cut into it, and was set about with ten holes. When Sherlock came closer and examined them, he realized that they were cut in such a way that they would accommodate ten umbrella handles. He could even see the way you had to stick the handle in, and then turn it. It was like the umbrellas were bloody keys.
"I did tell you, didn't I?" Mycroft said, stepping out of the doorway. "There's no way you will be able to get to him unless you return the umbrellas. Even I can't get to him without them."
Sherlock slowly turned, refusing to show surprise at his brother's success in sneaking up on him. Seeing Mycroft's oh-so-superior smirk set his teeth on edge.
"What is this, a bunker?"
"Of course. Where else would I go if I were here and a nuclear war started all of a sudden?"
"So this can't be the only entrance. You're so overly cautious you'd have at least one back way in. I'll just find that."
Mycroft sighed, putting on his tired-older-brother face. "It's true, there is another way in. But it's been computer programmed to only allow one person in or out, and it cannot be programmed otherwise without my command. Which I certainly will not give until my demands are met. Furthermore, I will not allow you to leave this room until they are met."
Sherlock scoffed; did he really think that he could keep Sherlock in here if he didn't want to leave? The pair of thugs suddenly standing in the doorway said that yes, he could. It was creepy how much like Moriarty Mycroft was at times.
"Think carefully, Sherlock. Is your pride really worth all of this?" He looked as though he was about to lean on his umbrella, before remembering at the last moment that it was not there. Sherlock strained his brain, trying to find a way out...and came up with nothing. Much as he might loathe to admit it, he was beaten. D- and blast Mycroft. He pulled out his phone, and sent out a text calling in all troops.