The film begins in 1946 with a banker from Maine, Andy, getting drunk and getting into his car with a loaded pistol. Then there are scenes of his wife committing adultery. Soon after, he is sentenced to prison and becomes a prisoner at Shawshank for a serious crime.
In prison, he befriends a black inmate named Red, and they help each other, becoming good friends. Meanwhile, a group of inmates led by Boggs frequently attacks Andy. Later on, the prison guards discover Andy's financial skills and come to him for investment advice, even seeking his guidance on their children's education. The warden uses Andy to cook the books for personal gain.
Years pass, and one day Andy solemnly tells Red: if you get out, go to a certain tree in a certain place and dig up a box. That night, Andy escapes from prison. After Red is released, he follows Andy's instructions and the two friends reunite on a beach in Mexico.