The film tells about the fighting everyday life of the crew of self-propelled guns during the liberation of Right-Bank Ukraine. Junior Lieutenant Maleshkin, an unshooted graduate of the school, commands the crew of the self-propelled gun SU-100. All the subordinates of Maleshkin are older than him and much more experienced. The authority of the young commander is tested at every step, he quarrels, then reconciles with his crew. In addition, Maleshkin is very dissatisfied with the battery commander, he now and then threatens to remove the sluggish young officer from the command. In the crew of Maleshkin, various troubles constantly occur: either the driver will catch the commandant's eyes in an untidy, grimy look, then a combat grenade with a dropped check will be discovered in the car, or a breakdown will occur just at the moment the regiment enters the march.