Missionary Stew follows political fundraiser Draper Haere on a quest to uncover the secret behind a right-wing coup in an unnamed Central american country. He seeks the information in order to get dirt on his boss's opponent in the 1984 US Presidential election.

Haere's pursuit of the truth repeatedly puts Haere's life in danger, as the powers-that-be stop at nothing to keep the episode buried. Along the way, Haere carries on an affair with the wife of his candidate and enlists the aid of Morgan Citron, an almost-Pullitzer winning journalist who has recently been released from an African prison where the prisoners where fed human flesh--the titular missionary stew.

Together, Citron and Haere face up against cocaine traffickers, Latin American generals, corrupt US officials, and Citron's estranged, tabloid-publisher mother.