Set in Rome during Nero's reign of terror, The Blood of the Martyrs is a disciplined historical novel tracing the destruction of one cell of the early church. With a cast of slaves, ordinary Roman people, exiles and entertainers, it is thorough in its historical interpretation and in its determination to make the past accessible and readable.

Written in 1938-9, the novel contains many symbolic parallels to the rise of European fascism in the 1930s and the desperate plight of persecuted minorities such as the Jews and the left-wing activists with whom Naomi Mitchison personally campaigned at the time. With the invasion of Britain a real possibility, she felt compelled to write a testament to the power of human solidarity which, even faced with death, can overcome the worst that human evil can achieve.