Sonja (Birgit Tengroth) is a housewife happily married with the factory worker Kurt (Åke Grönberg). But what he doesn't know is that Sonja has a dark secret of the past; she is a former prostitute. When suddenly Sonja's former, sleazy pimp Nick (Sture Lagerwall) shows up, he blackmails her into giving him money and letting him stay at their home. Otherwise he will tell Kurt about Sonja past. Sonja comply, but when Nick starts a relationship with Kurt's young and innocent sister Maj, Sonja has to act so Maj doesn't make the same mistake she did.