A Danish tourist has been brutally murdered in Southeast Asia; her mutilated corpse is discovered in the hut where former world diving champion Jacques Reverdy lives in seclusion. Once the athlete was already suspected of a serious crime, but was released due to lack of evidence. Reverdy remains stubbornly silent and is placed in a psychiatric hospital. Interested in the identity of the alleged killer, journalist Mark Dupeyra starts a cruel experiment: he begins to write letters to the suspect on behalf of a young, naive girl, trying to get him to open up.