From the first days of the WWII, an underground Komsomol organization "Partisan Spark" was established in a small Ukrainian village Krymka, captured by the fascists. It was headed by a ninth-grader Parfen Grechanyi. Young underground members, yesterday's schoolchildren, led a brave and courageous fight against the occupants. Beginning with the defeat of a fascist convoy that was taking bread from the village, the Sparkers were terrifying the enemies with their combat operations. It was 1943. The organization grew and became stronger. One day a rash act of a desperate boy Shura Kuchera leads the enemies on the trail of the underground group members....