Birdman of Alcatraz (1962)

After killing a prison guard, convict Robert Stroud faces life imprisonment in solitary confinement. Driven nearly mad by loneliness and despair, Stroud's life gains new meaning when he happens upon a helpless baby sparrow in the exercise yard and nurses it back to health. Despite having only a third grade education, Stroud goes on to become a renowned ornithologist and achieves a greater sense of freedom and purpose behind bars than most people find in the outside world.