This series, already so impressive, this season has quantum leapt over itself, becoming a TV series that pulls you in, holds you tight, and never lets go. Two weeks ago, it was David’s descent into a surrealistic rabbit hole. Last week, it was a mesmerizing trip through, and through and through again, the maze that is Syd’s mind. And tonight, most of the hour is devoted to Aubrey Plaza as Lenny, who has identity problems and psychedelic visions of her own, as she seems to return from