On a cold winter day, Jochen, Uwe and Kathrin play with a little dog called Bosun on the beach. Jochen wants to try out the ice and he walks further and further away from the beach. Bosun follows him. Suddenly the ice breaks and Bosum drifts away on an ice floe. What can the kids do to get Bosun back in time for the tugboat's departure? All resuce attempts fail until a steamer comes to help.

This puppet animated film is based on a classic East German children's book by Benno Pludra.