Small-time criminal Niilo gets the chance of a lifetime when the wealthy Sahlbergs mistake him for their long-lost nephew. Taking on the role of Yrjö Sahlberg, Niilo becomes the manager of a safe factory, where his old partner in crime, Oksa, begins to blackmail him into shady dealings. After falling in love with his "cousin" Annikki, Niilo wants to face his past and start a new life as an honest man.