What happens on the seventh anniversary of the Sudden Departure? Nothing, maybe, or it could mean the end of the world. In the latest trailer for The Leftovers’ third and final season, Kevin Garvey, who may just be some sort of shaman, and all his melancholy friends brace for even worse news than they typically get. ABBA’s “S.O.S.” plays over the trailer, because if there’s one thing Damon Lindelof loves more than not giving you answers, it’s jarringly upbeat music cues. The Leftovers returns April 16.