It's only baby-children who always do what they're told. Non-children decide when to obey, and they know how to disobey. This is the last day of our life as children.
1981. Twelve-year-old Roberto, returning to the mountain village where he spends his summer holidays, renews his friendship with the intense, brooding Mattia. Bound together by contempt for 'baby-children' and a thirst for grown-up adventure, they drive each other to test their courage and daring. But then they decide to take on the mountain, and the expedition ends in tragedy and guilt.
Thirty years later Roberto is an art dealer in Zurich. When his father dies he is forced to confront the unresolved issues of that distant summer, to unearth a guilt kept secret for too long. But to do this he needs Mattia. And to go back to the mountain, one last time.