A molecular biology department at a university somewhere in Europe in the near future. Thomas Nielsen, a young idealistic geneticist, encounters an imprisoned serial killer Vincent Iparrak. Nielsen pretends to study Iparrak's DNA, but he has an entirely different scheme in mind. The researcher manages to convince the killer to act as a guinea pig. If the geneticist can prove that the killer was violent from birth, the latter will be spared the electric chair. In exchange, Iparrak allows Nielsen to modify his DNA so as to eradicate the "animal" in him. A succession of incidents will lead these completely different men down the path of the other. The killer develops compassion and the geneticist becomes increasingly aggressive.