From Wikipedia: Nikita (re-titled La Femme Nikita in some countries) is a 1990 French movie written and directed by Luc Besson.

Nikita Taylor (Anne Parillaud) is a teen-aged delinquent and heroin addict who participates in robbing the pharmacy of the parents of a fellow junkie. The robbery goes awry, degenerating to a gunfight with local police during which her cohort is killed. Suffering severe withdrawal symptoms, she shoots a policeman. Nikita is arrested, tried, convicted of murder, and imprisoned for life, with parole considered after thirty years.

In prison, she is drugged to simulate a death sentence; she awakens in an anonymous room. A well-dressed, hard man (Tchéky Karyo) enters and reveals that, although officially dead and buried after suicide by overdose, she is in custody of the DGSE, the French intelligence agency. She is given a choice: work as a DGSE assassin or be killed. After some resistance, she chooses the former and proves a talented killer. One of her trainers, Amande (Jeanne Moreau), transforms her from grimy gutter trash to femme fatale; Amande, too, was so rescued and recruited.

Her initiation mission, killing a diplomat in a crowded restaurant and escaping back to the Centre, is the film's highlight, she is graduated and begins life as a sleeper agent in Paris with her boyfriend (Jean-Hugues Anglade), a man she meets in a supermarket and who knows nothing of her real profession.