Nunzio was the long-suffering driver for the mob. One of the mobsters he is transporting puts the mask on him as a joke, but he becomes Big Head. As Big Head, Nunzio kills the all thugs and eventually goes on to kill all of the crime lords as well as nearly all of their followers, and becomes the city's preeminent crime boss.
Eventually, Kathy (former girlfriend of the first Big Head), discovers Nunzio is Big Head and takes matters into her own hands She dresses as a hooker, and Big Head falls head over heels for her. She tricks him into taking off the mask, pulls out a gun, and as Nunzio dives for the mask she shoots and kills him.