Tell No One Wallpapers

Pediatric Alex Beck (Francois Cluzet), still devastated by the savage
murder of his wife Margot (Marie-Jose Croze) in the early days of
their marriage eight years ago, receives an anonymous email.
When he clicks on the link he sees a woman's face standing in a crowd
and being filmed in real time - Margot's face. Is she still alive? And
why does she instruct him to 'tell no one'?