When a deadly mist engulfs Paris, people find refuge in the upper floors of the buildings. With no information, no electricity and hardly any supplies, Mathieu, Anna and their daughter Sarah try to survive the disaster.
One night, a burglar in a Santa Claus costume is surprised by Victor, a young boy who believes he is the real Santa Claus. Victor then follows him, and they embark on an unexpected adventure that will change their lives.
