This deft, atmospheric Errol Morris-style tour through the phenomenon that is "serial imposter" Frédéric Bourdin homes in on one brief episode from the man's berserk career: the period in 1997 when the 23-year-old Frenchman convinced a Texas family that he was their disappeared teenage son. This is already well-trod territory, hashed over in a 2008 New Yorker article, a 2010 fiction film starring Famke Janssen and Nick Stahl, tons of press coverage, and even Bourdin's own YouTube channel. But the story still harbors queasy mysteries at its center, as true-crime TV pro Bart Layton micro-analyzes every step of the case, via interviews with the Texans, Bourdin and the FBI. How Bourdin manages to pull off this charade is the first conundrum, but the question of how credulous this wounded American family really is eventually becomes subsumed by others — as in, what really happened to the vanished boy? Why is the mother, Beverly Dollarhide, such a zombie? (The clan's troubles with addiction and the missing son's budding criminal career are factors Layton largely avoids.) And what's buried out back, literally and figuratively? Thick with reenactments and cute cutaways, The Imposter evolves into a cultural inquisition, following this stranger through the strange land of bad-news America, where the truth is still waiting to be exhumed.