Otto Scheidel (Manfred Krug) has been captain of the Elbe steamer Jenissei for over twenty years, but his ship, the last of its kind, is going to be converted into a floating restaurant. Otto, whose his strong attachment to the ship has already cost him his relationship with his girlfriend Caramba (Renate Krößner), refuses to take another job and instead joins a railway construction brigade.

When several barges get stuck at low tide, Otto commandeers the restaurant ship Jenissei, now managed by Caramba, in order to tug them free, and his warning call "Fire below deck!" send the customers fleeing the restaurant. When the maneuver fails and the ship is destroyed, Otto and Caramba initally start fighting once again, but Caramba finally comes to realize how important this line of work is to Otto.