The Hidden Woman (2012)

Marc Delvaux is an ex-cop. Since his wife died, he lives alone, confined to the ground floor of their large house due to the after-effects of an old leg injury. He's visited by Bernard Lerieux, a renowned attorney-at-law in Lyon, with whom he shares a love of chess. Bernard tells him he's working an "explosive" case. The outcome of the case depends on a surprise witness only he knows about. This witness must be kept a secret until the trial - and Bernard asks Marc to hide her at his house. Marc agrees. That evening, 28-year-old Emma shows up. She'll occupy the upper floor, where no one ever goes. But soon - unaware to Marc - the young woman begins to act strangely - She slips a sleeping pill into his coffee, pulls out one of his hairs, photographs the pages of a text he's writing - is she really at Marc's house by chance? Especially as she tries to isolate him even more. But Marc is not totally fooled, despite not fully knowing her reasons. He lets Emma continue manipulating him to gain her trust, in the hope that she'll tell all later. But the day the chance arises, Emma vanishes into thin air - Is she really the indispensable witness we're led to believe? What really ties her to the attorney Lerieux?