In June 1991, in the northern reaches of France, a tiger arrives by cargo ship from Africa and is acquired by a local circus overseen by Lohman, Christian Sinniger. Before the troupe can begin training the animal, it dies in its cage one night, its body inexplicably ruptured. Unbeknownst to Lohman, an ancient serpent-like parasite lurking inside the tiger has slipped free and makes a disturbing journey into the uterus of Yanka, a young performer in Lohman’s act, Emmanuelle Escourrou, while she sleeps.
A month passes. Yanka has escaped the carnival and now camps out in a derelict building in a nearby city. Lohman tracks her down, but Yanka has become something other than human: she is now partly guided by the parasite and able to communicate with it telepathically. In a brutal, knife-driven moment, she murders Lohman, a shocking turn that makes clear the parasite’s influence is growing stronger. The creature urges Yanka to drink blood to fuel its growth and to reach a birth that will allow it to emerge into the world and finally be released into the sea, its birthplace. When the parasite commands her to kill a vagrant and drink his blood, Yanka instead attempts to drown herself, revealing how the parasite’s control conflicts with her own will.
Time moves forward to Paris, where Yanka has reinvented herself as a waitress. There she draws the attention of Richard, a man who falls quickly for her. A romance blooms, even as Yanka continues to murder civilians under the parasite’s orders. When Richard suggests marriage and children, the parasite drives Yanka to kill him, shredding the sense of possibility the couple shared. Rosette, her jealous coworker who is drawn to Richard, comes to Yanka’s apartment and discovers Richard’s corpse, prompting Yanka to vanish.
Months later, Yanka reappears pregnant and working as a taxi driver. One evening, the parasite compels her to strike a jogger and feed on his blood. As she senses the onset of labor, she begins to murder other people and is ordered to steal a mobile blood-donation van. She succeeds, driving toward the ocean with a donor still inside, while the parasite explains that it must retreat to the sea to evolve and, eventually, supplant humanity after a vast span of time. The donor regains consciousness and attacks Yanka, triggering a crash.
Police and medics rush the scene, and Yanka’s heart stops en route to the hospital. The parasite somehow restarts her heart, and she returns to life, killing the medic and the ambulance driver in the process. In the back of the ambulance, she gives birth to a normal-looking baby boy, but the telepathic link they shared during pregnancy has vanished. Yanka seizes another driver’s vehicle and, at a rest area, the parasite escapes the infant’s body, causing the baby to burst and killing another traveler.
Yanka abandons the truck and boards a bus full of men bound for Le Havre, certain that the parasite has boarded secretly as well. She attempts to warn the passengers, only to uncover the parasite’s true form as it burrows through the driver’s head. In a final, devastating act, Yanka aims the bus toward catastrophe, crashing and causing an explosion as dawn breaks. The parasite finally withdraws to the ocean, leaving the world to wait for a moment that will not come for billions of years.
