The prison warden Paul (Tom Hanks) welcomed an extraordinary murderer that day - John Coughley (Michael Clarke Duncan). John was sentenced to death for killing two young girls and came to the famous Cold Mountain Prison. There is a green area called "Green Mile" in the prison, and the execution ground is at the other end of the green area. John is not as cruel as imagined, on the contrary, he is surprisingly kind and witty. John's arrival has brought earth-shaking changes to everyone in the prison: he injected the strength of life into the little mouse of the old prisoner Trevor, bringing the last comfort to Trevor's last life; miraculously saved Paul and Melinda who were tortured by illness; pulled Kimbos back from the hands of death... Paul has also seen the true meaning of life from John these days. The day of John's execution has finally arrived.