Stepfather III - Plot

Plot

Having survived the stab wounds he sustained at the end of the previous film, the stepfather (Robert Wightman), escapes from the institution in Puget Sound, Washington he was placed in four years ago, seeking a reclusive back alley plastic surgeon (Mario Roccuzzo) to perform extensive plastic surgery on him to alter his appearance, using no anesthesia. After taking several days to recover from the operation the stepfather kills the doctor by slitting his throat with a bone saw and makes his way to Deer View, California where has now acquired a new pseudonym, "Keith Grant", as well as a small cottage and a job at a plant nursery. Nine months after crafting his new life, Keith, during an Easter dance held by the church, meets and grows attracted to divorced school principal Christine Davis (Priscilla Barnes) who has a computer-savvy son named Andy (David Tom), who is a full-time wheelchair user due to psychosomatic ailments. Keith and Christine begin dating when Christine's possessive ex-boyfriend Mark Wraynal (Stephen Mendel) follows Keith home and claims he is going to marry Christine and that Keith should leave her alone. Feigning compliance at first, Keith murders Mark with a shovel and buries the body in his garden.

Despite Andy having some misgivings about Keith, his mother marries him, with Keith moving in with the two. Attempting to befriend Andy, who he believes he can help walk, Keith grows increasingly frustrated by the boy's introverted tendencies. When Andy's biological father Steve (Jay Acovone) offers Andy the chance to spend the summer with his family and attend a school for the gifted Andy decides to take his father up on the offer, despite Keith's protests. With Andy gone and Christine revealed to be infertile Keith begins courting Jennifer Ashley (Season Hubley), a widow who has moved into Keith's old cottage with her son Nicholas (Adam Ryen). Keith's plan to murder Christine and marry Jennifer grows complicated when Andy, suspicious that Keith is the escaped Family Serial Killer continually mentioned on the news, moves back to Deer View. Growing increasingly unstable after Christine and Jennifer meet and become friends, Keith murders his boss Mr. Thompson (Dennis Paladino) with a rake when he mentions that he spotted Keith cheating on Christine with Jennifer.

Convincing family friend Father Ernest Brennan (John Ingle) to help him uncover Keith's identity Andy invites the father over for dinner and the two sneak Keith's fork off the table, to have the fingerprints on it compared to the Family Serial Killer's. Realizing Father Brennan is up to something Keith excuses himself after dinner and follows the priest, running him off the road and killing him by beating his face against the steering wheel of his car. Making Father Brennan's death look like an accident by blowing up his car Keith attends his funeral (set on Father's Day) and afterward, when Christine mentions visiting Jennifer, rushes to the plant nursery and calls Jennifer, telling her to meet him. Before going to the nursery Jennifer calls Christine to cancel their meeting, claiming her new boyfriend called with an emergency. When Jennifer arrives Keith reveals he is married before claiming he needs her out of the way. Knocking Jennifer out Keith prepares to dump her in a wood chipper.

Arriving at the nursery with Andy in tow Christine, having pieced together that Keith is Jennifer's new boyfriend, confronts Keith about his affair and is beaten unconscious when she discovers Jennifer weakly writhing on the ground. As Keith prepares to murder his two lovers Andy, finding the fork he gave Father Brennan in the back of the car, finally realizes the truth about Keith and, overcoming his disorder, is chased through the nursery by his stepfather. When Keith climbs a ladder to look for him Andy knocks him off it and into the wood chipper and is almost dragged into it himself, only to be saved by Christine, who pulls him out of Keith's grasp. Despite Jennifer severing the power cable of the wood chipper Keith is still killed, being hacked to bits, finally ending him and his killing spree. The end shows the group walking out of the garden.