After a big car accident, caused by his brother Valerio, Antonio is mentally-ill, fallen to a childlike regression. They live together in Trieste. Valerio is totally absorbed by his job and by looking after Antonio that call him Papà (Daddy). One day Valerio decide to have a trip on a house-boat with Marianna, his fiancée, and they bring Antonio with them. Antonio unexpectedly drives the boat far away till it gets stuck on a sandbank. Valerio leaves his brother and Marianna alone on the boat and...