Prisoners Harry (Frank Sinatra), Marcel (Gregoire Aslan) and Charlie (Bernie Hamilton) are flown to a small tropical island to serve the elderly Father Doonan (Spencer Tracy), who makes them work high in the mountains at a health clinic for local children. When a volcano erupts, the young patients are stranded, while the rest of the island's population flees. When Doonan offers to free the convicts if they help save the children, Harry leads his fellow convicts on a daring rescue mission.