I was recently watching a documentary on film history, which said ever since we saw those planes hitting the towers on 9/11, watching real life drama unfold on-screen has become much more captivating than fiction. The Imposter is an attestation to that claim. A family in Texas, whose 13-year-old disappeared three years ago, are told their son has been found ... in Spain. But is it the same person? I wouldn't spoil anything beyond that, because this true story is so mysterious and twists on itself and changes gears so many times, you'll just be dumbfounded at the end.
Update: This is available for free on YouTube, here. Thank you, Maryam, for the heads up.
Update #2: Fascinating interview with "The Imposter" himself, Frédéric Bourdin, here. Beware: spoilers abound.
Update #3: Reza tells me the YouTube link doesn't work anymore. Bummer.