In a picturesque Massachusetts town, Bernadette O’Hara walks quickly down a darkened street. Hearing footsteps behind her she is startled by Mrs. Paterson, Headmistress of the prestigious prep school situated in the town, out walking her dog. Bernadette is on her way to the Silent Woman, local pub, where she’ll meet the rest of her friends known as the Top Ten. Leaving Mrs. Paterson, she meets another person, someone she knows, wearing a school scarf and leather gloves. Suddenly the gloved hand swishes past her throat leaving a red line, her throat cut.
At the pub we meet the rest of the Top Ten and students of the Exeter school; Randy (loud, athletic), Ann, Etienne (French exchange student), Amelia (wealthy New England type), Maggie (lively Canadian), Rudi (all around clown), Steve and Virginia Wainwright (quiet and innocent). The school kids cheer wildly as Randy arm wrestles a local farm boy?it’s the usual confrontation between the villagers and the rich kids from school. Later Alfred Morris, another Exeter student, enters the pub taking off his school scarf and gloves. He’s considered weird for his peculiar penchant for taxidermy and his unkempt unsettling manner. Nevertheless he’s one of the Top Ten. Alfred’s presence creates more confusion as he lets a small mouse loose in the pub. When it winds up in a glass of beer, Phelps kicks the whole bunch out of the pub. Still in a party mood, Etienne on his Harley Davidson leads a convoy of Ann in her VW, Steve in an MG, Rudi and Maggie in his Porsche 924, Randy and Virginia in his Trans Am and Alfred on a Vespa motorbike trailing behind. They play the game of crossing a draw bridge over a canal which runs through town as it parts to allow a barge to pass beneath it. Danger mounts as the gap increases. The Trans Am is the last to go over. Freaking out on the other side, Virginia jumps from the car and runs into a cemetery. The kids leave her alone except Alfred who startles her while she visits the graveside of her deceased mother, Estelle Wainwright. Nervous of Alfred, she reluctantly accepts a ride home with him on the motorbike. At home we meet Hal Wainwright Virginia’s father, and Mrs.Grove, the elderly housekeeper. Hal is disturbed by his daughter’s visits to the cemetery, but Virginia says its nothing to worry about because Dr. Fields (she calls him David) said its part of her treatment. Meanwhile, Alfred sneaks about outside, peeking in the windows while Virginia prepares for bed. While she is in the bathroom, he apparently sneaks into the house hiding in the closet. We anticipate him lurking in every shadow, but instead he escapes with a missing scarf from the bureau. Alfred putters off on his Vespa, pleased with his find. The next day the students attend a science class. Mrs. Patterson notes Bernadette’s absence. Prof. Heregard demonstrates muscle contraction in a frog’s leg by passing an electrical charge through the severed nerve. This recalls a moment in Virginia’s mind which we see in flashback: At the Institute of Regenerative Science, Dr. Fernman and Hal Wainwright view X rays of Virginia’s skull while Virginia lies unconscious. The doctor explains that the brain tissue is rebuilding itself. Suddenly Virginia awakes and sits up abruptly. The screen turns to white as it dissolves through to David Field’s home (Virginia’s psychiatrist and research scientist). David explains to Virginia how she was used as an experiment for successful regenerative brain growth. But the treatment will not be complete until she has recalled all the regressed memories of the accident. She leaves distressed. At a motorcycle race Etienne races to the finishing line wining narrowly over another contestant. While the Top Ten watch, Virginia impulsively congratulates him with a kiss. They make plans to meet later?although Etienne misses Bernadette, his girlfriend. Alfred watches hatefully. Later at the workshop, Etienne adjusts the idling motorcycle. His scarf catches in the chain pinning him to the stalled machine. The gloved hands and school scarf of someone unknown enters starts and revs the motor. Etienne protests as he is mangled in the spinning wheel. At Alfred’s cottage on campus, Ann and Virginia sneak about Alfred’s macabre display of his taxidermy work. Lit only by moonlight, the girls are startled by a gloved hand grabbing hold of Ann. It’s Alfred who’s annoyed by this intrusion. The girls say they want to see his latest work which Alfred mysteriously uncovers for the girls. At The Silent Woman, the Top Ten (now reduced to eight) celebrate Etienne’s win, except he’s not there. Later they hide outside Mrs. Patterson’s cottage. While keeping the real dog (Winston) occupied with dog biscuits, they plant a stuffed replica (Alfred’s latest work) on her lawn.
When Mrs. Patterson comes out to feed Winston, the stuffed Winston falls over, appearing dead. As the kids run away, the real Winston comes into view as Mrs. Patterson vows reprisals. The next day the gang miss Etienne and discuss the big joke on Mrs. Patterson. Alfred watches from behind a tree as he overhears an insulting remark about him. Later Virginia drives off in her BMW 2002. An ambulance comes up from behind startling her as she recalls in flashback: we see Virginia being moved from an ambulance to a waiting jet which will take her to the Institute. Back in the present, David consoles her and tries to explain that all this trauma must be recalled. He tries to convince her she’s well. Later in her bedroom she cries as we zoom in on a blissful family photo of Hal, Estelle and Virginia.
The next day, Mrs. Patterson tells Bernadette’s father about her absence. She’s on the warpath about the Winston gag as she accuses Ann and Virginia, not only for the stunt but for the missing students. That evening at the pub, Virginia comes on to Rudi, who reacts rather pleased. Alfred watches from a window. On her way home in the BMW, a leather-gloved hand reaches over the back seat moving slowly towards Virginia. It pulls back as she stops by the cemetery. Virginia cuts a bouquet of wild flowers with a pair of garden shears hanging on the fence. A darkened figure follows, who we see is Alfred. As he leans over Virginia kneeling by the grave, she turns in a rage and stabs the shears deep into Alfred’s gut. She wears the leather gloves and the school scarf flaps in her open coat. We realize she is the murderer.
The next day, after a soccer game, Virginia and Rudi go for a walk, finally winding up at the top of the chapel tower. As a joke, Rudi suggests they cut the bell rope almost through, then when the next ringer comes to pal on the rope it will fall on him. Virginia takes a pocket knife from Rudi’s back pocket, opens it and stares mesmerized at Rudi’s back. From below we see a bloodied knife fall to the floor of the sanctuary and hear foot-steps of someone run out the door, just as the bell ringer comes in. The rope falls as planned. He spies the blood-covered knife and calls for help. Virginia, as if in a trance, drives to the hospital to see David. The sounds of siren and the hospital atmosphere create another flashback in her mind: In an operating room a surgical team saw part of her head away. Brain tissue pushes through the opening and the doctor, in a panic, scoops a fist full of matter and throws it to the floor. Through all this Virginia is conscious enough to understand what is happening. Back in the present, David tries to convince her again that this remembering is acceptable and that she is normal now because of the regeneration process. Virginia talks about her lapses of memory which she hasn’t mentioned before. Then she leaves in a hurry saying that she must go find Rudi. The next morning David hears the news about another student missing named Rudi. David recalls Virginia’s conversation. At the school, a team of policemen scour the gardens looking for clues. David wants to talk to Virginia about the incident. Suddenly from behind the curtain comes Rudi. It’s all a joke. He cut his hand with the penknife and spent the night in the hospital. The officials are upset particularly David who thinks Virginia is part of the prank.
Virginia learns that her father will be away for a business trip, but promises to be back for her birthday on Sunday. At the school dance, Virginia and Steve dance intimately. Steve suggests they leave and Virginia invites him back to her house for a midnight snack. While a fire blazes romantically, Steve and Virginia embrace just as Mrs.Grove brings in skewers of roasted meat. Steve nibbles as her face hardens. She rams the metal skewer into Steve’s neck, the metal point coming out the back of his head. The next day Mrs. Grove leaves to visit her sister. Ann comes to stay with Virginia. While having a shower Virginia recalls a memory of driving with her mother (Estelle), Virginia dressed in a lacy juvenile party dress. She is 14 years old. Estelle drinks from a half full gin bottle. They pull up to the Thomerson family estate gate which is locked. There appears to be a party going on. Estelle, drunk and crying out of control, calls to them to not treat her daughter this way. On the way home, the draw bridge begins to rise just as they approach it. The car goes over into the canal. Virginia swims to the top, but Estelle drowns. In coming to the surface, Virginia is struck about the head by a passing barge. Back in the present, Virginia recovers sitting on the floor. In turning off the over-flowing shower, she sees Ann dead in the shower. At David’s house Virginia tells him that she killed them all. He doesn’t believe her, and of course, there’s no body of Ann to be found. David stays with her that night. The next morning a policeman confirms Ann’s disappearance. David begins to realize Virginia’s involvement. He confronts her; she changes personality and yells “It’s My Birthday!”.
In a flashback we see Virginia and Estelle in a small fairy tale cottage on the Wainwright estate. They await party guests?Ann, Steve, Bernadette, Etienne and Alfred, who are now an hour late. Her father telephones to say he won’t be home for her birthday. Then Virginia reveals that the kids have another party to go to at Ann Thomerson. Estelle says “If they won’t come to your party, we’ll go to theirs!”.
Back in the present, Virginia exclaims “We killed them all!”, as David steps back in fear. Later Hal arrives home calling for Virginia. Not finding her about the house he goes to the cemetery. Estelle’s grave has been unearthed, the casket open with David lying inside. He tells Hal to go to the cottage. In the cottage we find all the bodies grotesquely sitting up in chains, including Estelle. The place is decorated for a birthday party. A record player plays as Virginia enters singing “Happy Birthday to Me” carrying a cake and a large butcher knife. She leads Hal to his place at the table and says “Would Daddy like a big piece or a little piece?”