It helps that "The Chameleon" is based on a true story because much of what occurs in writer-director Jean-Paul Salomé's tight adaptation of Christophe D'Antonio's book might otherwise seem a bit dubious. That's not to say this moody thriller about professional liar Frédéric Bourdin is without intrigue, it's just better viewed with, er, logistical tolerance.
The film finds Nicky, a Baton Rouge, La., youngster missing since 1996, turning up four years later in France claiming he was abducted from his hometown with traumatic consequences. The U.S. return of the now-17-year-old (Marc-André Grondin) is met with curiously varied response: His mousy wreck of a mother (Ellen Barkin) can barely speak to him and his unruly half-brother (Nick Stahl) treats him like dirt, while Nicky's kindly sister (Emilie de Ravin) and her upbeat husband (Brian Geraghty) readily take him in.
Then there's the suspicious local FBI agent (Famke Janssen), who sets out to unravel Nicky's questionable tale.
The real mystery isn't if skittish, French-accented Nicky — a.k.a. Frédéric — is who he initially says (the answer becomes evident early on) but instead centers on the strange dynamic among his "family members" and their erratic interactions with him. Salomé and co-writer Natalie Carter offer some explanatory psychology, but the complexities remain underdeveloped.