All is not well on Zanatu: the idyllic Polynesian island is in rebellion, and the British Navy sends Lieutenant St Vincent Halfhyde to find out why. Halfhyde steams to investigate, braving typhoons and coral reefs along the way. But things go from bad to worse once he steps foot on the island, as angry natives armed with guns assault the British sailors. The natives swear allegiance to a mysterious god named John Frumm, who has appeared among them, promising wealth and prosperity. As the island slides toward anarchy, Halfhyde struggles to rescue the beleaguered members of Her Majesty's Colonial Service and find the elusive Frumm before it is too late.