In recent days, Rome has been the scene of an unusual event: when it rains, the manholes exhale a dense steam of unknown origin and composition. No one knows that those who breathe in the mysterious substance will have to deal with what they repress, their darkest instincts, their anger. Not even the Morel family. Since Cristina’s death in an accident a year earlier, the love of her husband Thomas and their son Enrico has given way to a forced cohabitation, while the youngest of the family, Barbara, would only like to see them united again as they were before. The accident could have been avoided, both Thomas and Enrico know it. Instead of taking responsibility and moving on, they stopped talking to each other. Now they are two souls full of rage, trapped in a Rome that resembles them: dark, nervous, on the verge of exploding.

Five carpoolers travel in a motorhome to reach a common destination. Night falls, and to avoid a dead animal carcass, they crash into a tree. When they come to their senses, they find themselves in the middle of nowhere. The road they were traveling on has disappeared and there is only a dense, impenetrable forest and a wooden house in the middle of a clearing, which they discover is the home of a spine-chilling cult.