 Mathias, whose dead father was a diplomat in Germany, decides to study the forensic medicine in Paris. In the train, he has some troubles with the border police, and is insulted and threatened by a strange man, who disappeared quickly. Next day, he discovers in his luggage a shrunken human head. He soons becomes fascinated by it, feeling responsible (sentry of the memory of the head s owner) and starts his own investigation. What will leads him to cope with French secret services.