On a rainy night in Paris, Dr Yann Voline runs over a naked young woman with his car; this accident turns his life upside down.

The young woman has no memories but knows everything about Yann; she has absorbed the doctor's memories as if they were her own and is able to read the minds of others.

An unknown bacteria is found in the young woman's blood; Martin, the lab technician, is infected and runs away; a strange man shows up at the hospital claiming to be the woman's father.

The alleged father of the strangers searches the hospital, destroys the blood samples and kills all the rats in the laboratory; meanwhile, WHO experts come to the hospital and discover during their investigations that something is wrong.

Yann and the young woman set off to find a high school student who has been missing for six years; they find her in a critical condition and discover she can only be saved by the mysterious woman.

The young woman disappears and Yann searches desperately for her, while the student is taken to hospital in a deep coma; blood tests show that she has been contaminated by the mysterious bacteria.