The plot is based on the actual events of the start of the Great Patriotic War. Red Army soldier Garkusha and Yakut Nomokonov, after the death of the whole team, remain together in the armored boat No. 042. Carrying out the order of command, the heroes blow up the bridge over the Dnieper, but are found at the rear of the enemy. An infantryman, a bank manager, an artist and a criminal escaped from prison get on the boat in different ways ...