Anton has to pass the physical fitness standards as a police officer, but his arm is injured. Marina replaces Jeanne in biology class. However, the training is not going according to plan.

Anton finds himself at a meeting of classmates, where he meets his inveterate enemy. At the same time, Marina is tormented by her conscience, Kiselyov advises her to apologize to Anton. And Kiselyov himself gets acquainted with his neighbor Tanya.