Tell No One tells the story of a paediatrician Alexandre Beck who still grieves the murder of his beloved wife, Margot; eight years earlier. When two bodies are uncovered near where Margot's body was found, the police reopen the case and Alex becomes a suspect again. The mystery deepens when Alex receives an anonymous e-mail with a link to a video clip that seems to suggest Margot is somehow still alive and a message to "Tell No One".