The mercenary protagonists, like the protagonist in the author's earlier novel "The Day of the Jackal" (1971), are ruthless, violent anti-heroes. Initially introduced as simple killers-for-hire, as the novel progresses they are gradually shown to adhere to a relatively moral mercenary code. Forsyth draws upon his journalistic experiences in reporting the 1970 Biafran War between Biafra and Nigeria; though fictional, the African 'Republic of Zangaro' is based upon Equatorial Guinea, a former Spanish colony. The novel's dedication to five men named Giorgio, Christian, Schlee, Big Marc and Black Johnny and "the others in the unmarked graves" concludes: "at least we tried"—and alludes to Forsyth's time in Biafra; the dark tone and cynical plot of the story stem from the same source.