Set in the mid-19th century, the film stars Marlon Brando as a British agent provocateur sent to overthrow a Portuguese colony in the Caribbean by manipulating a slave revolt to serve the interests of the sugar trade, and the complications that arise from the formation of a subsequent puppet state.

The fictional plot is partly based on the activities of American filibuster William Walker, after whom the main character is named, and his 1855 invasion of Nicaragua.

Screenwriters Franco Solinas and Giorgio Arlorio also drew on the experiences of intelligence agent Edward Lansdale, who served the United States government in the Philippines and Indochina in the 1950s through the 60s, and the Cuban Revolution.

In 1844, the British Admiralty sends Sir William Walker, an agent provocateur, to the island of Queimada (literally "Burned" or "Burnt"), a Portuguese colony in the Lesser Antilles.

After six years of the uprising, in 1854, the Company returns Walker (after finding him in Plymouth, England) to Queimada with the consent of the Admiralty, tasking him with suppressing the revolt and pacifying the island.

Walker attempts to save Dolores's life due to their past comradery, but the rebel leader rejects his assistance, asserting that freedom is earned, not received.

[3][4] Alberto Grimaldi originally suggested Sidney Poitier in the role of José Dolores, but Gillo Pontecorvo insisted on casting Evaristo Márquez instead.

Marlon Brando had the opportunity to have a role on Butch Cassidy and the Sundance Kid and The Arrangement once again with Elia Kazan, but chose instead to work on this film.

The Francoist government pressured the filmmakers to alter the script, and since Portugal accounted for a considerably smaller share of international box-office receipts than Spain, the producers did the economically expedient thing by making the Portuguese the villains.

[7] Natalie Zemon Davis reviewed the film from a historian's perspective and gave it high marks, arguing that it merges historical events that took place in Brazil, Cuba, Santo Domingo, Jamaica, and elsewhere.

is a quietly bleak, unflinching presentation of slavery, post-slavery racial hatreds, the role of race in political power and the colonial manipulation of all of the above.