Gabriel Syme is a poet and philosopher who becomes a police officer. The narration centers on Syme’s thoughts and feelings. Insights to the other characters often come through their conversations with Syme. Syme intends to infiltrate the anarchist movement and expose their plans. As the plot unfolds, his mission is more philosophical and his search more spiritual. His quest for answers drives the plot forward throughout the book.

Syme is fair-haired with blue eyes and a pointed beard. Many of the other characters are described as having dark hair or dark, sinister eyes. The novel’s religious tone is unmistakable, and many of the characters’ names have religious significance. In the Bible, Gabriel was the angel who brought sacred communication from God to man. At the end of the novel, Syme’s feeling that he possesses “impossible good news,” which represents the love of God, is also a sacred communication. Chesterton winks at the reader by giving Syme some of his own characteristics. Chesterton wore a cape, carried a swordstick, and often had a cigar in his mouth.