French secret service agent, Josselin Beaumont, known as Joss, is sent to Malagawi (fictitious country, representing the former French colonies in Africa at the dawn of the 1980s), to kill the country's president for life, Colonel N' Jala, dictator and enemy of French interests. But, the political situation having changed, the French secret services no longer had any interest in having N'Jala killed and, rather than simply recalling Beaumont, denounced him to President N'Jala, on orders from the Élysée. At the end of a speedy trial where he is drugged to confess, Joss is sentenced to forced labor. After two years of slavery, abuse, suffering and multiple tortures, he escapes and returns to Paris with only one idea in mind, to take revenge on his superiors by accomplishing his initial mission: to kill N'Jala, taking advantage of a diplomatic trip by him to France.
Notified by himself of his project, Josselin Beaumont's former hierarchy begins to have sleepless nights. Colonel Martin and his team will do everything possible to “stop” Beaumont. He taunts his former colleagues while navigating between his old home, where he finds his wife, Jeanne, and that of his mistress, Alice Ancelin, a member of the secret services. The formidable Commissioner Rosen, of the Repression and Intervention Brigade, despite brutal and expeditious methods coupled with fierce hatred and contempt towards Beaumont, will fail in his hunt and will be shot down by Beaumont.
Making people believe in his death by attributing his identity to Rosen, he takes Inspector Farges hostage, who came to the morgue to identify the body, and thus manages to go back to N'Jala, sheltered at the Château de Ferrières. Thanks to some sleight of hand, Joss gives his empty revolver to N'Jala and lures him towards the window. The latter can't help but point it at Joss. Farges, believing that it is Beaumont who is holding the revolver, shoots the president dead. As Beaumont prepares to leave the scene in the helicopter bringing N'Jala's prostitute, the minister, urged by Colonel Martin, finally gives the order to "stop" him. Martin transmits this order to Farges, who kills Beaumont with a burst in the back.
