Are you ready for the answer to one of television’s biggest mysteries that doesn’t involve a vengeful black puff of smoke? If so, mark your calendars for the May 17th instalment of THE BIG BANG THEORY. Entitled “The Staircase Implementation,” the episode will not just recount how Leonard, Koothrappali and Wolowitz first met Sheldon, but more importantly, reveal the sordid (and possibly gory!) tale surrounding the mystery of their building’s perpetually out-of-order elevator. More first look photos of which can be found after the jump.