Mathieu will stop at nothing to get his 11 year-old daughter Sarah out of the hermetic chamber she lives in since she was born, because of a grave illness. Suddenly, an earthquake hits and a deadly fog seeps over Paris. Mathieu and Sarah’s mother Anna are among the few survivors who find refuge on the upper floors of the tallest buildings, but they have to leave Sarah behind in her bubble. As hours pass, they get increasingly worried about their daughter. Mathieu and Anna count the time left in the batteries that power Sarah’s bubble. Knowing they can count only on themselves, they have to find a way to get outside through the fog.