15-year-old romantic Sasha dreams of traveling and chivalrous deeds for the glory of a beautiful lady, Alena's classmate. However, his innocent plans are disrupted by the war. To contribute to the fight against the invader, a brave guy becomes an assistant to a partisan detachment. He does not realize that very soon a treacherous denunciation will lure him into a fascist trap. But even during interrogations, boldly looking into the face of death, the noble Sasha will not flinch, realizing that this fifteenth spring is the last spring of his life.