In the heart of a city, the inhabitants of a tower wake up one morning to find that their building is shrouded in an opaque fog, obstructing doors and windows - a strange dark matter that devours anything that tries to pass through it. Trapped, the residents try to organize themselves, but to ensure their survival they gradually succumb to their most primitive instincts, until they sink into horror...
Alexis Pasquier, a young French teacher, begins his first day of classes at the Nancy prison. There he meets Léa, a young woman with whom he falls madly in love. Two worlds open up to him: true love and the prison environment. He will never be the same anymore.