Second World War. Germans and their collaborators are terrorizing the occupied area. But, almost every night, some of them gets shot. On every murdered man there is a signature "Sasa" and an ordinal numeral. The enemy kills a wounded Partisan fighter, believing that he is "Sasa". However, the mysterious enemy soldier murders continue. Group of young people leves to join the Partisans and comes to a meeting with the unknown "Sasa". It turns out that three boys, with whom the secret youth organization has had great difficulties in school, and who nursed the wounded Partisan, were revenging under the name of "Sasa"...