93 million miles from Earth, geomagnetic storms are projected from the sun's surface. When they hit Earth, they have little effect on living things, but can knock out the entire power grid. Today is just another day on Earth. But in two hours, a total blackout deprives 200 million European people of power. All hospitals, airports, emergency services and communication networks fail. Europe descends into an apocalyptic Dark Age. In the midst of this unprecedented disaster, two missing kids, an escaped convict, a very pregnant woman and several others struggle to survive. They say we can survive three minutes without air, three days without water. How long can we live without power?

Malo has separated from his wife and a divorce is in the works. His children leave with his wife on holiday, and he is lonely and depressed. His friend Rémi drags him to a party in the country, and driving back they see by chance a notice of a house being sold at auction by creditors. The low reserve price surprises them and they go round to have a look. Finding the door open, Malo picks up a letter from a little girl to her father saying she misses him - moved by the resonance with his own daughter, Malo accidentally takes the note with him when they leave in a hurry. He then resolves to return the note to the now grown-up little girl Cloé, but of course it's awkward to explain how he got it. He learns that she really doesn't want to sell the house, which is all that remains of her childhood. The relationship between them develops, and emotions run high at the auction. Ultimately the film explores whether Malo can give both or either Cloé and his daughter what they want/need,