To his family, François Voisin is nothing more than a humdrum civil servant. In truth, for the past twenty years he has been working as a crack secret agent. All goes well until François discovers that his son has been skipping school. Using all the resources at his disposal, the irate father tracks his son to find out where he goes when he is not in school. Then François learns that his wife Hélène is having an affair with another man. With the aid of the latest hi-tech surveillance equipment, the jealous husband finds that his rival is a second-hand car salesman masquerading as an international terrorist. To win back Hélène, François contrives an elaborate scheme in which she is coerced into playing the role of a secret agent herself. The scheme backfires badly, and François and Hélène end up in the hands of a ruthless terrorist group.