A deadly virus spread by rainfall forces siblings Simone and Rasmus to seek refuge in an underground bunker, parting ways with their scientist father.

After six years of isolation, Simone and Rasmus encounter other survivors. To stay alive, Simone must prove herself useful to the group.

Simone and the others set out for Apollon headquarters in Sweden, but their trek through Copenhagen is fraught with peril.

Jealousy flares in Martin and Beatrice. Simone and Rasmus meet a doctor with a connection to their father. A memory haunts Jean.

Rasmus and Beatrice grow closer as they spend time alone together. The others discover a new bunker -- and a disturbing secret that lies within.

A band of armed strangers tries to extract information from Patrick. Rasmus begins to unravel in the wake of a grim discovery.

The group arrives at Apollon headquarters, where Simone learns startling truths about the virus, her father and Rasmus.