Scarpi is the leader of a group of partisan fighters resisting the occupation by Italy's former ally Nazi Germany during World War II. Nominally a hero, he nonetheless is a very hard and ruthless man, at one point vengefully shooting and killing a fellow partisan who betrayed them to the Germans, even though the man had been forced to talk against his will and was clearly remorseful over what he'd done.
Scarpi and his men are supposed to meet a US Army demolitions team who are parachuting into Italy to blow up the Della Norte Dam. However, a German ambush at the meeting place leaves all but two men from both groups death. Scarpi is the sole surviving partisan, escaping into the forest, whilst the Americans' commanding officer, Captain Turner, ends up being saved when a freak gust of wind carries his parachute away into the forest where he gets hung up in a tree. Scarpi witnesses a group of children led by Aldo rescuing the unconscious American and carrying him away, but doesn't see where they take him.
Figuring the boys will seek medical treatment for Turner, Scarpi goes to see partisan doctor Frassi. He doesn't have long to wait. Aldo shows up begging Frassi for his assistance, whereupon Scarpi reveals himself and demands to know where the American is, needing him and his knowledge of explosives so that the mission to destroy the dam can go ahead. Aldo refuses, instead wanting Turner to train him and his friends to use machine guns so they can avenge the deaths of their parents on the orders of the SS' Major Taussig.
Scarpi smacks Aldo around a little until he agrees to lead him and Frassi to where Turner is, but he's lying - before entering the doctor's office, he left his two friends Carlo and Silvio on guard duty outside, and they issue forth birdcalls to alert him of the approach of some German soldiers.
As soon as he can, Aldo escapes out the window. Scarpi, unaware of the impending attack, moves to pursue him, only for German soldiers Hermann and Ehrlich to kick the front door in and enter with guns blazing. Both Scarpi and Frassi are cut down. The doctor dies instantly, whilst Scarpi lives long enough for German officer Captain von Hecht to enter and attempt to interrogate him about what the Americans' mission was. Scarpi merely bleeds from his mouth and expires without telling von Hecht anything.