Pekka Puupää and Pätkä, who return to Helsinki from an unsuccessful variety show tour, are forced into refresher training, where they are trained as frogmen. During the diving exercises, the friends encounter the mermaid Helmi, whom they help into the bathtub at home, to Justiina's shock. The friends, who have become civilians, eventually end up on a plane bound for Suez, being cornered by UN soldiers.
Factory manager Risto Järviö is under his mother's thumb. When his mother forbids him from dancing with factory girl Seija Vaara, Seija decides to make anonymous phone calls to Risto to annoy his controlling mother. Risto falls in love with the voice on the other end of the line and begins to make major changes in his life.
Three sailors rescue Carmen, who has fallen into the clutches of the white slave trade, and also manage to destroy a drug gang.
