Werewolf is a psychological thriller: it is the story of Romeo (Gigio Alberti) a police chief detective and his obsessive hunt for a serial killer, that he thinks may be Velasco (Bruno Armando), a professional engineer beyond suspicion. Nobody believes his theory, the man he suspects is too well known, too well to do, very powerful and the inquiry is not authorized. The chief detective is very obstinate and he continues in his inquiry with the help of a young, determined assistant Grazia Negro (Maya Sansa) and his trusted friend Rago (Stefano Dionisi), an inspector at the scientific police. The famous criminologist Del Gatto (Francesco Carnelutti) acts as consultant, from the little village on the hills near Bologna where he has been living secluded for some years, since his sensationally mistaken psychological profile of the Scandicci monster.
So on one side there is the anomalous team that cannot act officially, following leads and finding increasing confirmation of Velasco’s guilt. On the opposite front, the shrewd engineer launches his counter attack, he succeeds in invalidating evidence, and covering up leads with his influence, but above all he uses his acute intelligence to foresee any move the adversary might make. More than once the chief detective finds himself in a blind alley, but he does not abandon the inquiry because of his obstinacy and vocation. He shares his vocation mainly with his assistant who has become over time his trusted friend, thanks to the attraction that the girl feels for the detective. The case becomes a personal challenge between Romeo and Velasco, in an imaginary game of chess in which the challengers must choose their strategies, sometimes attacking, sometimes defending, always aiming at displacing the adversary, leaving the victory uncertain until the last move. Grazia’s determination, supported by her no more secret love for Romeo, will be decisive for the final showdown.