Mauritz Grafvenhjelm, alias Moppe, an impoverished nobleman, and his friend Ville enjoy a carefree life as vagabonds in summery Porvoo until Moppe finds a large sum of money and receives a reward for it. After celebrating thoroughly at the Belvedere restaurant, he wakes up in the morning in a cell with no memory of what happened and learns that he has become engaged to the restaurant owner, Miss Svea Jonson.