The "Alpagueur" is a mercenary, employed in secret by the government. His first task is to bust an important drug ring in Rotterdam. Next, he is put on the trail of "The Epervier" who is famous for staging hold-ups, using petty criminals. One of them escapes - Costa Valdès. He is captured and put in prison, but remains silent. The "Alpagueur", adopting a false identity, arranges to be placed in the same cell. He befriends Valdès and learns that the "Epervier" works as an airline steward. The "Alpagueur" retraces the "Epervier" who, in the meantime, has carried out a final crime of vengeance.