The three brothers Robin, John and Harold spend their vacations in 1925 on the country estate of their aunt Ellen. But instead of fun and games, the young men are expected to be extremely disciplined. And it gets worse: Harold falls ill and his brothers are to be quarantined. That's enough for the young adventurers! So they escape and hide in the forest. This is the beginning of a life they have always dreamed of. But it is not as easy as they had imagined. So the boys have to find shelter in a hollow tree trunk, their aunt worries and, on the advice of the vicar, calls in the police in the form of Sergeant Bunting. While the latter is searching, an unscrupulous journalist starts a hard-nosed hunt for Robin and John. The sergeant joins the hunt when Harold, who has fallen ill, also disappears..