Paul Edgecombe (Tom Hanks) is in charge of death row in a 1935 Louisiana penitentiary. The cell block is nicknamed "The Green Mile?due to its green linoleum floor--the path that an inmate must walk from his cell to the room with the electric chair. Paul, a decent, moral man, treats each prisoner with respect. His life changes, however, with the admission of John Coffey (Michael Clarke Duncan), a huge African-American man convicted of the rape and murder of two young sisters. Despite his powerful build, Coffey is gentle--and possesses a miraculous, mysterious power to heal.

Coffey heals Paul's bladder infection, resurrects a dead mouse, Mr. Jingles, that is the treasure of another inmate, "Del,?and cures the warden's wife of her inoperable brain cancer. Each healing requires direct contact between Coffey and the "patient,?and is accompanied by much electric and mystical effects. Coffey takes the infection, brokenness, disease into his body and is able to expel it, though it exhausts him.

Coffey's powers extend to visions and he directly feels the pain of others. He transmits his visions of the death of the two girls to Paul--who realizes that Coffey is innocent (indeed he had been trying to "heal?the children when he was apprehended) and that another inmate on the green mile is guilty of the crime. Paul, counseled by his supportive wife (Bonnie Hunt), asks Coffey what to do. Coffey, exhausted from suffering the knowledge of the evil of the world and cognizant of his lowly position as a poor black man, asks to have the execution proceed. His only request is to watch a "flicker show.?Paul arranges for him to see a Fred Astaire movie.

The executions are graphically depicted. One is particularly gruesome because of the evilness of the whiny, rookie guard, Percy, who deliberately causes a prisoner (Del) to suffer in the extreme. After giving the orders for Coffey's execution and watching him die, Paul quits his job.

The story is framed by Paul as an old man in a nursing home. Paul "tells?his story to another elderly "inmate?as an explanation for why he was overcome when watching the Fred Astaire movie in the common room. Paul reveals that he is far older than thought possible--as is Mr. Jingles who is still alive six decades later. Paul and the mouse were "infected with life?when touched by Coffey.