1. Nothing at all
It had been two months since Sherlock confronted the notorious Jim Moriarty in an old Nazi U-Boat, trying to stop him from blowing up the whole of London in 10 seconds. After that, nothing. No murders, no crimes nothing ! To Sherlock ,it was as if the whole world was standing still, and he could do nothing to stop it. John was in Barbados having the time of his life, and as much as he found John annoying, he missed having someone to talk to. Sherlock knew something was wrong, and he was determined to fix it.