Pediatrician Alexandre Beck (François Cluzet) still grieves for his wife Margot Beck (Marie-Josée Croze), brutally murdered eight years earlier. Only the friendship he has formed with his younger sister Anne's (Marina Hands) lover Hélene Perkins (Kristin Scott Thomas) saves him from total disconnect from the rest of the world. When two bodies are unearthed near the secluded lakeside murder site, the police reopen Margot’s case with Alexandre himself incriminated. The Pandora’s box of suspicion gets fully opened when Alexandre receives an anonymous e-mail with a video that suggests that Margot is still alive and a message to "Tell no one. We’re being watched"…