Two very different families spend their holidays in the same house at the seaside: the aristocratic Castelvecchios, open-minded, eccentric, but quite selfish, and the working-class Petagnas, very tight-knit, and united around solid conservative values. What brought such distant worlds together? Only Tony and Carlo, the two middle-aged heads of the families, know! The unexpected announcement of their engagement will disrupt an apparently ordinary summer, and turn the lives of everyone around them upside down.