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.
A well-to-do French family living in Calais deal with a series of setbacks and crises while paying little attention to the grim conditions in the refugee camps within a few miles of their home.
Fanny is a Jewish girl in a French orphanage in 1943. When she and her friends are no longer safe from the Nazis, they try to flee to Switzerland. After their guide disappears, Fanny has to take the lead and help the other kids make it over the mountains.
