In 1973, Father Jedediah Mayii casts the Devil out of young Nancy Fellsmee during an exorcism in her family home, but as he leaves her room, Father Mayii falls down the stairs. Satan’s voice tells him, “I’ll be back.” Seventeen years later, at the University of California at Chicago, “The Exorcising Priest, Father Jedediah Mayii,” speaks to students at a Champions of Humanity Lecture Series. Recounting the events of his famous exorcism, he claims it initially destroyed, but then renewed, his belief in divine intervention. A provocative coed in the front row briefly distracts him, and a “nerd” constantly asks pointless questions. Father Mayii reports that he lost track of Nancy Fellsmee after he exorcised her demon, but heard she married Braydon Aglet and had two children, Frieda and Ned. The priest continues to recount what began one evening not long ago: Nancy Aglet gets too close to a television set during evangelists Ernest and Fanny Rae Weller’s Miracle Hour. Satan suddenly leaps from the TV screen into her body. Nancy growls and expels green vomit on her family, but then reverts to her regular self and runs from the room. Nancy’s children are convinced she is suffering from pre-menstrual syndrome (PMS), but her husband sends her to the family physician, Dr. Hackett. After a battery of medical tests, Dr. Hackett and his colleagues admit they have no idea what the problem is. On the way home, Nancy stops at Our Lady of the Evening Church for confession, and leaves a note in the collection plate for the young priest, Father Luke Brophy. When Father Brophy visits the Aglet home, Nancy confides that Satan possessed her body when she was a child, and now has repossessed her. To prove her first claim, she shows Father Brophy a “Certificate of Demonic Possession” signed by the Pope. The priest is perplexed because he has always believed demonic possession was folklore. When Father Brophy gives Nancy rosary beads, Satan takes over the housewife’s body and throws him across the room. Father Brophy promises to get to the root of the problem. He arranges for Nancy, looking satanic with greenish skin and glowing eyes, to be tied to the posts of her bed, but despite her bonds, she announces in Satan’s voice that she is more powerful than the priest can imagine. She questions his faith in God, and vomits up a small bust of Father Mayii’s head. When the priest asks for proof of her power, Nancy makes the film break and bubble from heat. Father Brophy drives to the “Actors & Exorcists Retirement Home,” where Father Mayii resides. A nun at the front desk raps Father Brophy’s knuckles with a wooden ruler and tells him not to run in the hallway on his way to Father Mayii’s room. Father Brophy introduces himself and informs Father Mayii that Nancy has been repossessed and needs his help. As the old man’s heart begins pounding, he worries that his weakened condition could make him susceptible to being possessed himself. He suggests that Father Brophy, being young and healthy, perform the exorcism. When Father Brophy confesses he has lost his faith, Mayii suggests that this is a chance to save his own soul while he saves Nancy’s. Brophy meets with Fathers Crosby, Stills, Nash, and Young at the Supreme Council for Exorcism Grantings. Also present, as part of an interfaith exchange program, are televangelists Ernest and Fanny Rae Weller, along with Fanny’s pink poodle, Fufu. Father Brophy shows video of Nancy’s transformation, and adds that she also gave him a little head. He shows them the tiny bust of Father Mayii. Declaring that Nancy’s demonic possession is real, Ernest Weller wants exclusive rights to televise the exorcism, because he is concerned about the drop in his ministry’s collections since his scandal with a boy’s choir. Weller goes to Fred Tartastein, head of the Global Television Network, to pitch his idea for Ernest & Fanny’s Exorcism Tonight, broadcast live throughout the world via satellite. The network will receive all commercial proceeds while Weller’s ministry collects all telephone donations. Weller and Father Brophy visit the possessed Nancy Aglet, who is happy for the worldwide coverage. Suspecting that Satan is maneuvering him into a rematch, Father Mayii joins a gym to restore his physical strength. As the old priest works out with weights, Father Brophy arrives to announce that the Supreme Council has granted him permission to perform the exorcism, but that Weller has convinced the Church and the Aglet family to allow it to be televised. Brophy joins Father Mayii’s exercise program in an effort to recruit him into assisting with the exorcism, but the old priest wants no part of it. On the night of the telecast, as Variety reporter Army Archerd welcomes fans and celebrities to the event, Father Mayii watches the program from home. Among studio guests are the Aglets and Fathers Crosby, Stills, Nash, and Young. Ernest Weller declares, “From the bowels of Hell, the Devil!” and Nancy, still green-hued and tied to her bed, is wheeled onto the stage, growling. Stagehands rock the bed and provide special effects off screen. Donations pour in from viewers. Tartastein informs Weller they are being watched by the largest audience in television history. Nancy suddenly coughs fireballs, setting off the studio sprinkler system and sending the audience running. Then she puts the Wellers into a two-person horse costume. Alone in the studio, Nancy telekinetically brings the camera closer and speaks to the audience. Trying to block the camera, Father Brophy pleads for every “man of God” to rush to the Global Television Studios, but Nancy knocks him aside. Realizing that Satan’s spirit originally flew out of the TV and into Nancy, Father Brophy unplugs the camera. Grabbing an electric cart, Nancy announces, “I’m going to Disneyland,” and leaves the building. Father Brophy follows in another cart. The Pope arrives with other holy men and joins the chase through the studio lot. Nancy stops and climbs into the satellite dish and calls on the powers of darkness to join her. Clouds form overhead. When Father Brophy directly addresses Satan, taunting that Father Mayii will come and whip him again, the Devil brags he could have beaten the priest, but the fight was fixed. He demands a rematch and challenges Father Mayii to come to the studio. Announcers proclaim a coming battle of good and evil, and Las Vegas odds makers, knowing Mayii has a bad heart, make him a twenty-five-to-one underdog. At home, Father Mayii mixes raw eggs with vitamins and prepares to fight. He takes a taxi to the studio. Father Brophy joins him as assistant. As Satan, speaking through Nancy, and Father Mayii insult each other, television wrestling announcers “Mean” Gene Okerlund and Jessie Ventura describe the play-by-play action. When Satan shows Father Mayii a photograph of his mother in Hell, in bed with former Panamanian dictator Manuel Noriega, the old priest seizes his heart and passes out. Fortunately, Brophy grabs a set of nearby defibrillators and revives Father Mayii. Satan transforms the old man into various characters, but the priest continues the exorcism. When Satan leaps into Father Brophy’s body, Father Mayii pulls him back out, and the Devil returns to Nancy. Responding to Satan’s confession that he hates rock ‘n’ roll, Father Mayii, backed by a band, sings “Devil With A Blue Dress On.” Satan leaps into Mayii’s microphone, and Nancy reverts to her normal state. Back in the university classroom, Father Mayii introduces Nancy Aglet to the class. When the nerd student in the front row challenges their story, Father Mayii and Nancy vomit green pea soup all over him.