In France, terrorist groups and intelligence agencies battle in a merciless war everyday, in the name of radically opposed ideologies. Yet, terrorist and secret agents lead almost the same lives. Condemned to secrecy, these masters of manipulation follow the same methods. Alex and Al Barad are two of them. The former is the head of the D.G.S.E.'s counter-terrorism unit while the latter reigns over a terrorist network, and both fight using the most ruthless of weapons: human beings. Secret Défense tells of their secret war through the destinies of Diane, a student recruited by the French secret service, and Pierre, a troubled young man who thinks terrorism will bring him salvation. Trained and indoctrinated for missions which are beyond them, they are both drawn into a chain of events from which they seem incapable of escaping.