The first officer on a freighter accidentally kills his captain during a heated wage dispute and ends up sentenced to the dreaded Devil's Island. there he finds the married woman he fell in love with when his ship was docked at a French port. Unfortunately, she is married to the island's doctor, a corrupt fellow busily lining his pockets by selling medical supplies meant for the prisoners on the black market back on the mainland. An epidemic hits the island and many prisoners fall deathly ill. During an enormous storm, the former first mate risks his life to see that the medical supplies are returned to the island. Despite his heroism, the brave prisoner receives no pardon and so he and the doctor's wife team up to escape.