Unable to find her runaway son, a woman deceives two of her ex-lovers from her youth, a mild-mannered teacher and a tough journalist, that each is the real father in order to obtain their help.

A group of friends are planning how to spend their summer vacation. One plans to go to the Seychelles with his American girlfriend. At the airport she dumps him for another guy. He has no money so he steals a backpack and goes camping. Somehow he meets a pretty girl and convinces her to share his tent. But a famous singer sees the girl and wants her too. He convinces the luckless guy to act like a fool and the girl leaves him and goes with the singer to the French Rivera.

The "black robe" in the title of this suspense film belongs to a female lawyer, Florence Nat who has just lost a case in which she defended Simon Risler, a man wrongly accused of murder. Risler escapes before he can be put in prison, and seeks help from attorney Nat in finding the real killer, partly by going after the police inspector who framed him in the first place. A retired surgeon, in the process of setting up a drug rehab clinic gets involved in solving Risler's case, and soon the solution seems to be pointing to high-ranking figures with every desire and ample means to keep the truth well-hidden.

A detective, fresh out of the academy (lowest mark in class), gets the assignment to bodyguard a spoiled rich girl reporter. She's been interviewed on TV and has questioned the virility of a mobster who kidnaps her later.

The story centers around a graduating class of "less-gifted" students in a private Versailles high school. Only a miracle has brought the students this far along, and after a practical joke misfires and the whole school is dynamited, the students are in deep trouble. They have to present themselves in court for their punishment and it could not be worse: If they don't pass their high-school graduation exams, they go to prison!