Along with his fellow Ghostbusturtless, Harold mistook Venkman for some kind of supernatural entity menacing Michelangelo. He participated in Venkman's capture using his proton pack, threw him into their vehicle, and headed back to their home base. However, he and Bill Music found Michelangelo trying to free his friend and, believing him to be possessed, attempted to subdue him.
He remained suspicious of Michelangelo even when the young Turtle attempted to reassure them, but changed his mind when Michelangelo directed him to the proton pack on Venkman's back. He witnessed the pair leaving their dimension outside the Ghostbusturtles' headquarters.