Heinz Senkbeil

Karlemann is very often found in his own 'Robinson world', a secluded place on earth. There he travels the river in his special all-weather boat, and he has his domicile on the river, all built himself. One day he meets two soldiers of the National People's Army who got lost in Karlemann's empire. He shows the them the right way. What Karlemann does not yet suspect: a bridge is to be built over the river at the exact spot where his hut stands...

Tank commander Sergeant Tessen does not believe that his crew can become a successful collective and requests his transfer, but he finally withdraws his request due to a young boy to whom he carelessly promised a tank model. However, this would first have to be made by the crew members. New difficulties arise, even though everyone agrees to keep the soldier's word of honor. The spell is only broken when the tank gets into a dangerous situation during an underwater journey and the four of them have to prove themselves together.