Ovidio Ceciotti is a teacher, he is plump and he is not a man of character. He is treated badly by his school-master, by his students, by Lidia, his girl and even by his dog. One day his twin arrives. He calls himself Ralph Benson and has a completely different character. He is impudent, genial, he is popular with women, he is not plump, he spent six months in a jail. Even the dog likes him more than Ovidio. Ralph plays in a bar with the beautiful Esmeralda. They will have to live together. How long will it last?