Charlie (Tom Cruise)'s father died and left a legacy of 3 million US dollars. However, to his surprise, the legacy was all given to a brother he didn't know, Raymond (Dustin Hoffman). Charlie had never heard of Raymond's name, and this incident made him angry. He decided to go find his brother. Who knew that Raymond lived in a mental hospital. It turned out that he had autism since childhood and was sent to a mental hospital for treatment after his mother died. Charlie had a plan in his mind. He took Raymond out of the mental hospital and tried to trick him into giving away the inheritance. Raymond's living habits were strange. He lived in his own fantasy world and had many bizarre behaviors. In addition, Charlie discovered Raymond's amazing memory ability in coexistence. He tried to use his brother's photographic memory to try his hand at the casino and won a large bonus, which enabled Charlie to get rid of his poor life. What Charlie gained more was that he also gained a slowly warming family affection, which was far better than the 3 million inheritance he originally planned.