The emigrant Nicola Carletti (Renato Rascel) and his family return to Italy after thirty years in the USA, to promote a new invention. The authorities discover that he missed the military service and, although he is in his fifities, they oblige him to attend the training. Life in the barracks is not easy for him: he has to endure the terrible Marshal Rossi and doesn't have enough time to sign important business deals. To complicate things further, the fiancée of the Marshal's daughter falls in love with Carletti's daughter, leading to jealousy between the youngsters and furious fights between Carletti and the Marshal. In the end, Carletti succeeds to sign the importnat business deal, the Marshal's daughter falls in love with a rich American and Carletti and the Marshal become friends and business partners.