In it was Ben as both Sherlock AND Julian Assange (who had a Khan-like haircut), Moriarty as a friend and partner of Holmes(!), myself (because it was my brain dreaming), and Minnie Driver for some reason (?). Thinking back on it though, there were a bunch of Sherlock characters missing. John, Mycroft, Mrs. Turner, Molly (or maybe my brain was trying to tell me that I was Molly? I don't know), Lestrade, and Anderson.
There WAS a Big Bad, and the culmination DID involve some serious subterfuge (Sherlock at one point was painting wounds on Assange's face in prep for the big plan), and it ended with everyone arranging to meet up at a secret spot. Everyone was anxious for the others to make it out the far side of the plan alive, because there was a significant chance of death (of course. It wouldn't be a Sherlock plan without it).