In the beginning of the Nazi occupation of Belgrade, a group of young immigrants arrive in Belgrade to execute special assignments for the Partisans, the first objective: rescue a fellow Partisan from an occupied hospital.
Tihi reconnects with an old flame Lili to gain access to a German motor garage while the rest of the gang infiltrate an ammo dump to obtain explosives for the sabotage.
As the charismatic Major Krieger tightens the noose, the Partisans begin to suspect a traitor called Beli is among them. A new liaison from HQ is assigned to the Partisan cell and she orders the assassination of the chief of police.
Destroying a German explosive depot proves to be an immense task for the Partisans due to the imminent flooding of a sewage system they must use to reach the depot.