A strange and deadly mist envelops Paris. A group of survivors finds refuge on the upper floors of apartment blocks and on the roofs of the capital. With no information, electricity, food or water, a couple attempts to survive this disaster and save their daughter… But as the hours go by, one thing becomes quite clear: there is no help on the way, and if they want to make it through this catastrophe alive, they will have to try their luck in the mist…