In the early '60s, 3 Danish classmates join a "den"/tree house. Steen likes his pet fish Zappa because it eats the weaker fish. Bjørn attracts girls and Mulle is a talkative, strong boy. Steen gets them into burglary and later escalates.

Denmark, 1961. Bjørn, a middle-class boy in his early teens, wants to be accepted by Steen, a bullying peer of his with wealthy but freezingly cold parents. Bjørn's other good friend is Mulle, a cheerful and more childish working-class boy. All three seem friends at first, but gradually Steen starts pushing Mulle away while pulling the impressionable Bjørn with him towards more and more tragic violent behavior, fueled by frustration over his loveless home life.—Markku Kuoppamäki