Idealistic priest “Fr. Joseph” (Kerwin Matthews) has arrived on a remote French Polynesian island to take over from the weary and cantankerous old “Fr. Matthew” (Spencer Tracy) whose congregation consists of a leper colony and a prison. When the priests manage to recruit a few reluctant convicts to help out with some repair work in the leper village, they - led by “Harry” (Frank Sinatra) prove to be a bit bigoted and recalcitrant, but things soon change when their very own version of Krakatoa decides to make it’s presence felt putting everyone into a spin and giving the cons an idea as to…