The movie opens on a scene at night with a man kissing a woman on a sidewalk. Suzie Lawler (Tally Todd) rebuffs her lothario, so he storms off in his car. As Suzie turns to walk home she sees the visage of a cavewoman in a nightgown. She screams, not recognizing her girlfriend, Trudy Morton (Sandra Knight). Trudy is dazed and confused. She has black bushy eyebrows and thick dark teeth. We zoom in on her face as the title is shown. Credits roll in white font over a black background.Trudy wakes up in her bed. She thought she had a nightmare and is relieved it is over. Her uncle, Carter Morton (Felix Locher) enters and reminds her, "It's late dear. I thought you had a date for tennis." She confesses she didn't sleep well, "It seems so real, as though it actually happened." Carter dismisses himself and Trudy gets ready for her tennis date. Oliver Frank (Donald Murphy) waits downstairs for his collaborator to start work. Carter unlocks the door to the lab. An impatient Oliver reminds Carter again, "If you'd let me have a key I could have begun work an hour ago." Carter argues with Oliver over their approach. Finally Carter asks point-blank, "Oliver, do you want to quit? Say so. Just say you quit and go." They don their lab coats, Carter resigned to be stuck with Oliver Frank until this line of research is completed. His goal is a formula that wipes out all disease in mankind, "Man will be ageless." Oliver throws cold water on Carter's dream, "I'm afraid you're on the wrong track. Your formula may work on internal cells, but it causes violent disfigurement to sensitive exposed skin areas."At the tennis courts, Suzie tells her boyfriend, Don (Harold Lloyd, Jr.) and Trudy's boyfriend, Johnny Bruder (John Ashley) about the monster woman she saw the evening before. Trudy arrives and is told about Suzie's horror story. Trudy warns, "Nightmares are nothing to laugh about. I had one myself, last night." The story intrigues Trudy and she asks for more details. Trudy begs off playing tennis, obviously upset. Johnny asks Trudy what's the matter. She tells Johnny, "It's as though Suzie and I had the exact same dream." She recounts the evening's events. She stayed home, had some fruit punch with Oliver Frank, felt tired, and then went to bed.Carter pronounces his latest test as no good. Of course, Oliver tells him, "Well, I could have told you that. Even if it did work it would have only been temporary." Carter has to remind him of their working relationship. Elsu (Wolfe Barzell), the gardener, interrupts to tell Carter he has completed some household chore. Carter suspects Elsu is a spy. Oliver suggests throwing out the latest test formula, but Carter overrules him, "I'm sure if I could get some Digenerol as a catalyst, it would work." He promises to get some from the Rockwell Labs, but Oliver cautions him not to do anything that brings police scrutiny. Trudy is in the living room reading Screen Stars magazine. Elsu comes in and presents her a flower. She is uneasy and repelled by the unwanted attention from the gardener. Uncle Carter throws him out. Elsu encounters Oliver on his way out. Oliver asks, "Tonight?" Elsu quietly replies, "There will be an automobile accident." He chuckles and promises to get it. Carter leaves to get his Digenerol, leaving the unctuous Oliver to paw at Trudy. She rebuffs his attentions with a cute remark about her plans for the evening, "In the pool for a swim. And I'd suggest you take a cold shower." Oliver returns to the lab door, and using a key he had made, starts work on a body. Elsu arrives, letting himself in through a secret entrance behind a bookcase. He is carrying a bundle wrapped in a towel. Oliver tells him he needed an entire head, not the part he secured. It is revealed that Oliver's real last name is actually Frankenstein. He instructs Elsu to return the body to the storage room. Judy swims in the pool as Oliver mixes up a potion. He offers her some "fruit punch" as a peace offering. He convinces her to drain her glass. She immediately gets woozy and heads for her bedroom. She starts to transform before she falls into bed. Transformation complete she gets up and sees her reflection in her makeup mirror. She lunges at Oliver in the doorway. By now her eyes are bugged out and her skin wrinkled and leathery. Oliver used too much of the formula.Police Lt. Boyle (John Zaremba) is on the phone in his office. He is taking a report from a man reporting a monster woman wearing a bathing suit. Boyle tells Police Detective Bill Dillon (Robert Dix) about the call. Boyle gets another call from a woman reporting the same monster in a bathing suit. The pair go to investigate. Oliver and Elsu prepare an antidote to give Trudy. Boyle and Dillon check on the woman (Charlotte Portney) who reported the creature. Her face is scratched and bloody. After she finishes her story, Boyle pulls his gun and searches for the creature. They spot Trudy and fire their weapons at her. She runs and topples some trash cans. The commotion draws Oliver with his antidote. Oliver captures Trudy. The next morning the local newspaper headline screams, "Woman Monster Menaces City!" Carter asks Oliver about the story. He is incredulous, telling Oliver, "Rubbish. Like the myths and the legends of the Dark Ages. These are headlines to sell newspapers my boy." The mention of Frankenstein gets a rise out of Oliver. Carter shows Oliver his new acquisition, a bottle of Digenerol. Trudy wakes, now back to normal, but still wearing her one piece bathing suit.Mr. Rockwell (Voltaire Perkins) is in Boyle's office to report a robbery at Rockwell Labs. He explains that, "That drug is very dangerous. It degenerates tissues and cells. In the wrong hands it could seriously disfigure anyone who might take it internally." He intimates it may be the cause of the monster. Carter and Oliver are working when Elsu enters the lab via the bookcase entrance. To distract attention, Oliver bumps Carter, who drops the bottle of Digenerol, breaking it. Carter is furious. Suzie rings the doorbell at the Morton residence. Oliver answers the door. Suzie inquires about Trudy. She walks around back where Trudy is on the chaise by the pool. She shows Trudy the paper and monster story. Suzie gets mad when Trudy claims to be the monster. Jealous, Suzie figures to even the score by getting involved with Oliver Frank. Little does she know how dangerous this will be for her. Johnny arrives as Suzie departs. Suzie starts her seduction of Oliver by making a date for 8:00 that evening. Trudy begs Johnny to believe her story.Suzie meets with Oliver that evening. He comes on too strongly for her and gets his face slapped for his efforts. He is furious and threatens to kill her. She decides to call the date off, but Oliver won't take no for an answer. She reveals she wasn't supposed to go out and no one knows she's with Oliver. His demeanor changes from angry to maniacal. "Where can we get the brain," he asks himself, "I need a brain. I need a brain." Suzie runs down the road. Oliver follows in his car. He strikes and kills his victim. Oliver and Elsu carry her body into the lab. She is wrapped in a blanket. He tells Elsu he intends to graft Suzie's head on the other body. He tells the corpse, "Tonight you'll be alive again, you vixen." As he and Elsu finish their work, Johnny and Trudy arrive home from their date. Judy thinks she hears someone in the lab and checks. They finish up and Elsu proclaims the creation, "Frankenstein's Daughter." Trudy tries to sleep but hears electrical equipment downstairs. She calls to her uncle Carter. She phones Johnny at home to report noises. She locks her bedroom door and goes to sleep.Boyle and Dillon meet on another report of a burglary at the Rockwell Labs. More Digenerol was stolen by an elderly man. Carter arrives home in a sorry state. He is winded and calls weakly for his niece while clutching his chest in pain. He calls again, then collapses on the stairs. Oliver and Trudy both respond to the old man's cries for help. Oliver's creation (Harry Wilson) wakes and moves its' hands and arms. It gets up off the gurney and wanders around the lab. We zoom in on creatures face and bandage covered head. Half the face resembles ground meat, the "good half" a very ugly man in lipstick. The neck bolts glint in the dim light from the lab equipment. It wanders out of the lab into the entry of the house. We can clearly see the rubber suit, and black rubber gloves on its hands. Coiled electrical wires run from the neck to the wrists. It tears off the curtain on the front door, breaks a window and pulls the door open to escape. Oliver and Trudy respond to the commotion. They enter the lab and Oliver mumbles, "Then she's alive."Two workmen at the Associated Storage Company are loading crates. Mack (George Barrows) is working late and complains about his burnt dinner. His supervisor (Bill Coontz) hears a noise and investigates. He is carrying a crowbar for protection. The monster approaches him. He backs up and strikes the monster with his crowbar. It strikes back sending the warehouseman running for the door. The monster catches him and crushes his body in the closing door. Mack finds his coworker dead, and immediately calls the police.Before Bill Dillon can leave for the evening, Lt. Boyle gets a phone call and tells him to stick around. The warehouseman reports the crime. The pair go to investigate. Carter and Trudy sit and talk in the living room. Oliver and Elsu return after looking for their creation. There is a knock at the door and Trudy, expecting Johnny, answers it. Oliver's creation returns home. Trudy screams and faints. Elsu explains, "I told you she'd come back. She needs to be revitalized." Oliver helps Trudy to her feet just as Johnny arrives. They help Trudy to the living room. Oliver tries to convince Trudy, then Johnny, she saw nothing. Johnny tells Trudy that Suzie has disappeared. Elsu sits, with now now chained creature, in it's room. Oliver gives his creation an injection.Trudy has the gang over for a barbeque, Page Cavanaugh and his trio perform "A Special Date" musical number. Trudy and Johnny prepare dinner for the gang. Don scares Trudy with a rubber monster mask. His punishment is to sing. Oliver plans Carter's demise. He taunts Carter, then starts to strangle him when the police conveniently arrive at the house. Boyle questions Carter and Oliver about the Lab break-in. Oliver tells Boyle that Carter broke in to the lab and stole the Digenerol. Boyle leaves with Carter, not under arrest, but wanted for more questioning. Oliver and Elsu continue to work on their monster, but Elsu is starting to get cold feet. He feels the experiment was successful and is now over. Johnny and Trudy set the date for their wedding. Oliver gleefully tells Trudy her uncle was arrested. After Johnny departs to get his father, a lawyer, to see Carter and the police, Oliver makes his move on Trudy. He proudly reveals his real identity as Oliver Frankenstein, and boasts, "And while your uncle was wasting his time on a trivial experiment, I was completing a masterful one." She rebuffs him and he drags her to the lab to see his creation. She faints and Oliver and Elsu place her on the gurney. "You've always treated me as a monster, Trudy. Now you're going to be one," he tells her. Elsu objects to his plans for Trudy, and threatens to go to the police. Oliver orders his monster to kill Elsu. Trudy wakes and exits the lab as Elsu meets his fate.Johnny meets with Boyle. Boyle tells him that Carter had a relapse and is in the police ward of the hospital. The doctor will only let him meet with his lawyer. Trudy arrives at Boyle's office and reports the monster and Oliver's true identity and Elsu's death. A phone call reveals that Carter has died. Boyle and Dillon pay a visit to the Morton home. They question Oliver and ask for his identification. Boyle knows Oliver is lying, so Dillon stays and waits for the gardener to return to question him. Boyle returns to headquarters. Dillon walks upstairs when he hears a noise, then back down to see Oliver secret himself into the lab. He follows Oliver to the back room behind the bookcase. He pulls his gun and enters the monster's room. Oliver and the creature are waiting. Oliver proudly tells Dillon that he's looking at Suzie Lawler, then laughs explaining that, "She's not as pretty as she was." He releases the monster and orders it to kill the detective, which it does. Trudy and Johnny drive to the Morton residence. Trudy answers the phone. Boyle asks about Dillon. Trudy sees the lab door open, and the pair investigate. They spot the secret entrance and explore. The monster struggles to escape its' shackles and succeeds. It walks downstairs and chases Johnny and Trudy into the lab. Oliver is waiting for them. He tells them that Dillon and Elsu are dead at the hands of his creation. He threatens, "You know Trudy, you escaped me once, but I don't think you can do it again." He orders the monster to kill the pair. Oliver tries to escape but the arrival of Boyle thwarts his attempt. While Johnny fends off the monster using the gurney, Boyle shoots it from the window. A flask of acid thrown by Johnny at the monster misses its intended target, but hits Oliver. His melted face is shown before he hits the floor screaming in agony. The monster goes to check on its master. Johnny and Trudy embrace as they watch the monster accidently set itself on fire. It screams as it tries to extinguish the flames. Johnny and Trudy meet Boyle in the foyer and tell him the monster is on fire in the lab. Boyle witnesses the death throes of the creature now fully engulfed in flames. It burns like a tire fire. Boyle tells the pair, "It's all over now. I'll call the department." They exit the house.Johnny and Trudy are by the pool. Trudy towels off her fiancé. Don stops by with the newspaper, anxious to have them read the story. Johnny it not interested and tells him to leave. Don falls into the pool. We close with Johnny and Trudy kissing and telling Don once again, "You can leave anytime."