Who is the martyr in the story, The Martyr?

Njoroge is the man who ultimately becomes the "martyr" of the story's title. He has planned that night, with other Ihii (Freedom Boys), to kill Mrs. Hill as an act of rebellion against the settlers. However, as he awaits the arrival of his fellow rebels, he begins to think of Mrs. Hill's children; seeing her in the light of her role as mother to a family, Njoroge finds that he cannot bring himself to kill her. He decides instead to run to her house and warn her before the Freedom Boys arrive.