J'ai une idée

Louis Mennechain is a modest locksmith. So imagine his amazement when Professor Piétrefond approaches him and tells him he recognizes in him a descendant of the kings of France, more precisely of Louis XVII (the king who never reigned). According to him he is none other than the monarch's great grandson. Louis's life is soon turned upside down as he becomes the center of attention of a group of ardent royalists. Even a duchess "gives" him her love to make sure that he accepts his role as pretender to the throne...

Back from the war, Marceau Le Guern remembers. Educated in an orphanage run by Dominican brothers, he fell into misery when he left it. His only asset was his good looks, which did not escape the attention of Madame Alice, a shady woman who persuaded him to pose for pornographic photos meant for lonely aging women. Marceau also served as a gigolo before the war and captivity put an end to this juicy business. Now he wants to start a new life, all the more as ha has found love in the person of a pure young lady named Dominique. But Madame Alice won't hear of it...

Domino has only a wooden statuette, a typical piece of African art, to show for his trip. Arriving in Paris, Domino phones the famous Heller galleries to try to sell his statuette. He gets Heller’s wife, who uses him to deflect the suspicions of her jealous husband: she had an affair before their marriage. Domino gets carried away and persuades the young woman to go away with him.

Count Hubert de Latour Latour is the lover of the Duchess de Maulévrier. The day he is surprised by the Duke in the company of his wife and... in a rather compromising situation, Hubert resorts to a subterfuge, claiming that he has come to see the Duchess to seek support to be elected at the Institut de France, whose chairman is precisely her husband. The latter takes him at his word and Hubert becomes... a member of the French Academy! Which just shows that everything leads to everything.

Sylvie is a young cashier in a Montmartre café, "le bar des Philosophes", owned and run by Monsieur Marcel, a former safe cracker. One day, the pretty creature accepts to give a helping hand to two regulars, Francis and Josélito. But what the naive girl does not know is that the two men are gangsters and that they plan to steal 50 million francs deposited in the safe of Maître Roland Devert, a charming young notary. Actually things do not go according to plan all the more as a love story between the notary and Sylvie was not at all on the two gangsters' agenda.

Marcel, rich and alone for Christmas, invite Françoise to celebrate whim him. Soon, the fairy tale turns into a bad dream.

Five people are gathered in a cafe because of a phone call they have all received. The plot thickens when they discover a dead body in a bedroom upstairs.The five people all become suspects.