The greedy and treacherous family of a wealthy woman named Anastasia "Granny" Gargoli (Stella Stevens) wants her to die so they can inherit her insurance. They decide that murder is the only way to get at grannies money.
Granny lives in a large mansion along with her granddaughter, Kelly (Shannon Whirry). When her family arrives at the mansion for Thanksgiving dinner and a long weekend together, it is clear that Antoinette does not like Kelly. The families plan is to put poison in her soup. During the meal, Antoinette gives Uncle David (Brant von Hoffman) a foot-job underneath the dining room table. All eyes are on Granny as she is about to take a sip of soup. However, after taking a sip, she spits it out, much to the horror of the greedy family members.
Granny finds out about this evil plan, and orders an eternal life potion by a mysterious preacher Namon Ami (Luca Bercovici). Although the preacher admonishes her not to take the potion in sunlight, Granny ignores him and drinks it in broad daylight. She melts into noting but arises from a grave as a vampire-like monster, that has been granted immortality.
With Granny dead, as they assume, they ship her off to the morgue and the family immediately begins to squabble over the $15 million she left each of them. Granny returns to the house and starts killing her family to prevent them from inheriting her fortune.
The family consists of Albert (Sandy Helberg), a plastic surgeon who is killed by being slashed to death with scalpels; Andrea (Patricia Sturges), a woman who loves fur is chewed to death by furs that come alive; Junior (Ryan Bollman), the obnoxious kid who likes to wrestle dies when Granny pins him, and then she throws him down a flight of stairs too.
Antoinette is later seen seducing Uncle David. She tells him that she is willing to combine resources of her inheritance with that of Dave if he would give up his bachelor life. Dave tells her that he is willing to give the situation a trial run. Antoinette, assures him that he would not be disappointed, as she opens her blouse and shows off her very large breasts. Dave's eyes were barely contained inside his eyesockets.
Antoinette is seen dancing naked in her room just prior to her rendezvous with Dave. Granny spies on her outside her window, and we later learn that Antoinette is killed by Granny off-screen. Later, Antoinette is seen in bed with Dave. As her head bobs up and down, it eventually changes from Antoinette to that of Granny. Granny then uses a pair of scissors and cuts off his "member". She then uses the same scissors to decapitate his head.
Antoinette later is seen sitting at the dinner table along with the other zombie family members. The only member standing is Kelly.
Antoinette later attacks Kelly. However, she is stabbed in the back with a sword that comes out between her cleavage by Namon, and it appears that she dies for a second time. However, she once again comes back to life, and finally is burned by the sunlight and dies a third time at the end of the film along with all of the other family members.
Full gallery: Antoinette (The Granny)