In 1909, Robert Stroud kills a man in Alaska and is sentenced to 12 years imprisonment. He forfeits his chance for parole when he knifes another prisoner. While serving time at Leavenworth, he murders a prison guard who refuses to let his mother visit him, and he is condemned to death. Before his execution can be carried out, however, his mother visits Mrs. Woodrow Wilson, who persuades the president to commute Stroud's sentence to life imprisonment. The prison warden, Harvey Shoemaker, informs Stroud that he will spend the rest of his life in solitary confinement. One day during exercise period in the isolation yard, he finds a wounded sparrow and takes it to his cell. Secretly he nurses the bird back to health and then teaches it to perform tricks. When Warden Shoemaker is replaced by a kindlier man, Stroud is given permission to keep his pet and also to have other birds in his cell. Through endless study, he becomes an authority on caged birds and eventually writes a textbook on their diseases. After winning a prize in a magazine competition, he is visited by Stella Johnson, a lonely widow who suggests that they manufacture his remedies. A change in the prison set-up threatens to deprive Stroud of his birds, but he finds a legal loophole that will permit him to marry Stella while he is still in solitary confinement. The newspaper publicity which is created permits him to carry on his work. Then he is abruptly transferred to Alcatraz where his old nemesis, Shoemaker, is warden. When Stroud is informed that he can no longer keep his birds, he shifts his interest to caged men and writes a book on penology. Shoemaker, however, has the work confiscated. Stroud acts as a peacemaker in a prison riot and is transferred to a minimum security farm at Springfield, Missouri. As he leaves Alcatraz, he is met by Tom Gaddis, a social worker and writer who became Stroud's defender by writing Bird Man of Alcatraz in 1955.