Rose, portrayed by Marilyn Chambers, and her boyfriend Hart, played by Frank Moore, embark on a scenic ride through the Quebec countryside on Hart's motorcycle. Their leisurely outing takes a dark turn when they collide with a camper van that has unexpectedly stopped in the road. To avoid a crash, Hart swerves, veering off the path and crashing the motorcycle. Witnessing the incident, a patient at the nearby Keloid Clinic for Plastic Surgery calls for an ambulance.
At the clinic, businessman Joe Silver presents an intriguing franchise opportunity to Dr. Dan Keloid, played by Howard Ryshpan, and his wife Roxanne, portrayed by Patricia Gage. However, Dr. Keloid hesitates, fearing he might end up like "the Colonel Sanders of plastic surgery." At that moment, the ambulance delivering Hart and Rose arrives. Hart suffers from a broken hand, separated shoulder, and concussion, while Rose is severely injured and trapped under the motorcycle. Recognizing the urgency, Dr. Keloid decides to proceed with a radical surgery on Rose that employs her own skin to repair her damaged tissues. Although effective, this risky procedure may result in cancer.
As time passes, Hart returns home to Montreal while Rose lingers in a coma at the Keloid Clinic. A few weeks later, patient Lloyd Walsh, played by Roger Periard, hears Rose screaming in her room and rushes to check on her. Upon finding Rose awake and frantic, he tries to help her, but in the process, she inadvertently injures him. Following a brief examination, doctors attributing his condition to a mild stroke transfer him to another facility for further observation.
In the days that follow, Rose begins to experience a bizarre transformation due to the experimental procedures she underwent. These changes leave her with a dire need for human blood, as she can no longer consume anything else. The dangerous mutation leads to the development of a peculiar organ in her armpit, which protrudes to extract blood from her victims, similar to a syringe. Initially, she attempts to feed on a cow at a nearby farm but soon realizes that only human blood will suffice. Her first human victim becomes an unsuspecting, inebriated farmer whom she preys on in the barn. The following night, she attacks a nurse in a hot tub and conceals her unconscious body in a freezer.
Meanwhile, Lloyd leaves the clinic and catches a taxi headed to the airport. However, he undergoes a horrifying transformation into a zombie-like creature, attacking the driver and causing a fatal crash as their taxi plunges off a bridge. Back at the clinic, Dr. Keloid inspects Rose only to be struck by her phallic organ, beginning his own spiral into madness.
At a local diner, the infected farmer wreaks havoc after biting a waitress. Soon after, Rose contacts Hart, pleading for his help, and he rushes to her side with Mindy Kent, Rose’s best friend, as they attempt to uncover the bizarre chain of events stemming from the clinic. During their frantic search, they encounter a series of violent outbreaks and realize a terrifying epidemic is unfolding in the city, fueled by Rose's condition.
As chaos intensifies, officials implement extreme measures to control the outbreak, with Claude LePointe overseeing the containment efforts. Meanwhile, Rose strives to maintain her secret while unintentionally creating havoc around her. The situation deteriorates further when Mindy unwittingly becomes the next victim of Rose's bloodlust.
All eyes now focus on Rose, who is at the core of the pandemonium engulfing Montreal. In a gripping climax, Hart confronts Rose and tries to save her, but she remains in denial, absorbed in her monstrous transformation. The film culminates in chaos as the military moves in to contain the outbreak, unaware that the key to stopping the epidemic may lay buried within Rose herself, her body potentially holding the cure amid a city engulfed in fear and violence. As the streets grow eerily silent, Rose is ultimately discovered lifeless, leaving her fate—and the fate of Montreal—hanging in the balance.
