Director Svensson in Stockholm is going on vacation to Koön in the archipelago. The rented cottage is inhabited by the brothers August and Johan Österman. Johan throws out August and tells him to arrange accommodation for the summer guests elsewhere.
A local newspaper editor in northern Sweden starts to spread a rumor that sextuplets has been born. In reality it turns out that it's only two sets of twins.
Julius Berge has an advertising firm in Stockholm together with his wife Sonja. The man with the ideas is their colleague Kurt Dal, who used to be engaged to Sonja. Their ménage à trois becomes a crazy mix of jealousy and misunderstanding.