It's the end of the holidays at "L'Escapade", a small campsite in the Landes. While Michel, the boss, makes the tour of the owner in front of the cameras of a continuous chain of information, a terrible cataclysm falls and the campers find themselves deprived of electricity and telephone network. Anyway, they're cut off from the world. Agathe, lieutenant of the gendarmerie, decides to join the nearest town to find help...

Agathe and Julien, the campsite's sports entertainer, try to cross the mysterious fog. Meanwhile, Michel and Sam, the cook, go in search of a doctor. In the forest, they make an unexpected encounter...

After the dramas of the previous day, Agathe finds his gendarme instinct and leads the investigation. In one of the caravans, she discovers strange documents that evoke a cult, the order of Lou Carcolh. Meanwhile, Michel and Sam try to preserve the reserves stored in the cold room...

The generator of Clovis broke down and the tenants of the camp-site have only one solution: to go to the "Rouleaux", a camp-site located a few kilometres away and held by Paul, Michel's sworn enemy. At the same time, Father Cohen, a priest from the neighbouring parish, had the documents entrusted to him stolen. Agathe...

Prisoners of the robbers entrenched at the Rouleaux, Agathe and Sam seek a way to escape while Michel is forced to send a video message to L'Escapade to ask for a doctor: one of the robbers is indeed dying. Meanwhile, at L'Escapade, Natalia and Clovis submit the prowler to the question. The man, strangely mute, accepts to speak only to Father Cohen...

As they tracked the prowler, the Escapés come upon a new survivor. They decide to find his friends and collect them at L'Escapade. For her part, Agathe goes after the prowler and discovers his disturbing lair: it is clearly the lair of a madman...

Back at L'Escapade, Agathe discovers that a strange epidemic has caused several deaths. Sam receives a mysterious call from his mother and sister. Weird... All the networks are down since the cataclysm.

The arrival of a patrol of soldiers led by Captain Beaumont gives hope to the Escapés: the soldiers have food and want to be reassuring. But the upturn was only short-lived...

The Escapés are now held prisoner by the military, and one of the members of the group, wounded, is between life and death. Agathe desperately tries to make Beaumont understand that the worst is yet to come and that climate degradation is heralding a second cataclysm.

As "La Limite" progresses and threatens to swallow the campsite, Agathe sets up a plan to join a breach in the fog. But the operation is risky and there is little chance that everyone will make it...