John Robbie (gary grant), a thief who used to be nicknamed "Black Cat", is living a leisurely life with his beloved black cat in his beautiful country house, but because of successive jewel thefts, the police came to you, which is very similar to his modus operandi. John easily got rid of the police and decided to investigate who did it himself in his own way.
John came to Mr. Ba's restaurant. Mr. Ba was also the head of the pre-war thief group. He fought alongside John in the war and opened a restaurant after the war, taking in a large number of prisoners who were released from prison. John couldn't find a clue, but he was regarded as trouble by these ex-prisoners. The police followed him to the door and had to leave. With the help of the daughter of restaurant waiter Fu, John came to Cannes Beach. Fu's daughter is an unruly and enthusiastic girl who has been pursuing John enthusiastically.
In Cannes, with the support of the insurance company manager, John started his own plan. He began to approach Steven and his wife from America according to a treasure list. Mrs Steven is a straightforward woman. The beautiful Miss Steven (Grace Kelly) has a quiet appearance and likes an exciting life when she is alone. Miss Steven saw through John's identity from the beginning, but she has been playing love games with John for more excitement.
Steven's mother and daughter's jewels were stolen right next to John. Miss Steven was very angry because she mistakenly thought that John had cheated them, but Mrs Steven helped John avoid being pestered by the police. John came to Xiaoshan Villa to wait for the black cat to appear, and killed Fu who attacked him in the fight. John gradually understood the truth.
Steven's mother and daughter helped John attend a grand masquerade party, and the insurance company manager pretended to be John to attract attention. The real John hides on the roof and watches everything. Just when John was about to lose patience, a black cat appeared, which was Fu's daughter. During the struggle, John forced her to tell him that it was Mr. Ba, who had never changed his old habits, and the black cat was finally acquitted.
Miss Steven followed John Robbie all the way to John's villa and couldn't help jumping into his arms ... Facing the beautiful scenery, Steven in his arms muttered, "Mom will love this place."