The Second World War. Dogs are being trained for guard duty in the Nordfelsen training center. Concentration camp prisoners are used as targets for attack, and are forced to provoke the dogs and get them to feel hatred for the striped prison uniform. One of the prisoners is Mares, a former member of the International Brigade in the Spanish Civil War. He has been allocated the Alsatian bitch Rita, and is secretly training her in a different way. He just pretends to beat her and at night, he goes and feeds her leftover scraps of food. Mares is planning an escape with his fellow prisoner Benda.