The Chameleon (Le Caméléon)

When a disoriented young man is picked up by French police and positively identified as a long unsolved missing-person case, the reunion with his family is bittersweet and fraught with suspicions about whether or not he really is their prodigal son. The case worker struggles with the sense that something isn't quite right, and is baffled by why his mother embraces him, despite suspicious behavior.