In the animated city of Townsville-Springfield, a criminal on the run, Charles Lee Ray, is mortally wounded by Detective Homer Norris. Using a dark ritual, he transfers his soul into a “Good Guy” doll, sold later as "Mac" to young Bart Simpson for his birthday. Strange events unfold. Bart's babysitter Maggie is thrown from a window. A toy store explodes. Detective Norris starts to piece together a bizarre string of murders, all while Marge suspects something's wrong with the toy. Bart insists Mac is alive—but no one believes him. Mac’s true motive is soon revealed: to steal Bart’s body using the same voodoo that saved him. As Marge and Norris race to protect Bart, they face off against the possessed Mac in a terrifying finale.
