Devil's Island was a penal colony in French Guiana active from 1852-1946. Even by island prison standards, it was notoriously brutal, and most inmates died there (the book Papillon, made into a movie in 1973, is written by Henri Charrière, who escaped from the island and told his story).
Dave Mustaine of Megadeth wrote this song from the perspective of a prisoner on the island, hopeless and confronting his inevitable death there.
Mike Campbell from Tom Petty & the Heartbreakers played the slide guitar on "Sixth Avenue Heartache." There is a connection here - Wallflowers lead singer Jakob's dad, Bob Dylan, played with Tom Petty in The Traveling Wilburys.