An American couple drift toward emptiness in postwar North Africa.

Good dope is becoming rare in the North of Paris. Drugstores are being raided by junkies and gangs are nervous, fighting each others: the 'Viets', the 'Blackies', the 'Arabs', the neo-nazis 'Justiciers' and some mean gays. Vincent (Daniel Auteuil) is the good cop coming from Marseilles where he was a gangster. He's a soft method guy but also kicks assses hard and throw lethal dialog lines when needed. With the precious help of 'l'Arbalète'* (Marisa Berenson**), a tox' prostitute ex-member of Vincent's former gang, he will try to put order in that mess. There's also a violent and racist cop (Marcel Bozzuffi), Algeria veteran with hard methods, whose role could be more than to protect and to serve.

The true story of explorer, journalist and writer Isabelle Eberhardt, originally from Switzerland. She moved to Annaba in Algeria in 1897 with her mother, who preferred to live in the Algerian neighborhoods rather than the European neighborhoods that she hated, and converted to Islam. Her lifestyle shocked the French colonialists: she dressed like a man, frequented cafes and smoke shops. Fascinated by the desert, she traveled the Sahara under the identity of Si Mahmoud, she published articles and books on the world she discovered in southern Algeria, strongly criticizing the colonial authorities. Arriving in El Oued, the soldiers prevent him from continuing his journey. She disobeys and overhears officers shooting Arab prisoners. Arrested, she was accused of espionage and was expelled from Algeria. She married Slimane, a Muslim non-commissioned officer in 1901. Having become French through this marriage, she could now reside in Algeria.

In the 18th Arrondissement of Paris, Lambert, an aloof garage manager working the night shift at a petrol station spends his time drinking on the job, content in his own company. One night, Bensoussan, a small-time drug pusher in dire straits falls in on a stolen moped pretending to need a spark plug. The two men develop an unlikely friendship.

In a working-class immigrant neighborhood slated for demolition, Jo, the son of Ali, known as the Rescuer from the Algerian war, lives idle and delinquent, committing small assaults to pay for his drugs. One day, while attacking Slim's bar, he is arrested by Ben, a young beur cop torn between his roots and the imperatives of his mission to maintain public order. Giving in to the respect and friendship he feels for Ali, Ben agrees to release his son. But alas, far from calming down, Jo drifts deeper into violence, until the inevitable drama.