In the well-known "Sanatorium for the treatment of childhood obesity" - on the banks of the Danube, Ilko, Emil and Yaroslav are again together with the rest of the kids, subjected to starvation and salad diets by the head doctor Stoyanov, the nurse Denitsa and the gym teacher Ponchev. In the difficult moments, the old fisherman Bai Angel gives food and support to the little braves.