What is the theme in The Martyr by Ngugi wa Thiong'o?

The most central theme in all of Ngugi's work is the effect of colonialism and post-colonialism on the African people. "The Martyr" takes place during a time of rebellion among Africans working on plantations against the European plantation owners. Through the characters of Mrs. Hardy, Mrs. Smiles, and Mrs. Hill, the narrator touches on widespread attitudes of the "settlers," or colonialists, regarding the African people who work for them.