In 1844, the British Empire Admiralty sends Sir William Walker (Brando), an ''agent provocateur'', to the fictional island of Queimada, a Portuguese Empire possession in the Lesser Antilles. Britain seeks to open the island to exploitation by the fictional Antilles Royal Sugar Company. Walker's task is to organize an uprising of slavery in the Caribbeans against the Portuguese regime, which the British intend to replace with a government dominated by pliable white fazenda.