The film shows a year in the lives of three students: from high school graduation day to their first school re-union.

Gosha and Zosya, in love for a long time, have become lovers. Both have serious plans for the future — he to become a volcanologist; she to enter University. When Zosya discovers that she is pregnant, much to her deep disappointment, Gosha advises her to have an abortion. She decides to leave him; gives birth to a boy, and against her mother's advice, takes a job on a construction site.

Dina, who has been secretly in love with Gosha, has no great difficulty in capturing him, and the two get married. Right from the time of the wedding, Gosha knows that he has made a mistake, and the marriage turns out to be an unhappy one.

On re-union day, Gosha and Zosya meet again, and Gosha tries to win back his real love. But Zosya rejects him and hurries home to her son, who has taken Gosha's place in her life.