Birdman of Alcatraz (1962)

Convict Robert Stroud is sentenced to life in solitary confinement after murdering a prison guard. Overwhelmed by isolation and hopelessness, Stroud's existence transforms when he discovers an injured baby sparrow in the exercise yard, which he lovingly cares for until it recovers. Despite his limited education, Stroud evolves into a celebrated ornithologist, finding a profound sense of liberation and meaning within the confines of prison that eludes many outside those walls.