The work is dedicated to H. G. Wells and covers anarchist, espionage, and terrorism in general. It also deals with exploitation of the helpless in Verloc's connection with his intellectually disabled brother-in-law Stevie. Conrad was influenced by Charles Dickens' Bleak House in his depiction of London in the novel.
Conrad adapted the novel as a stage drama, and it has subsequently been adapted into film, television, radio, and opera.
It was one of the three works of literature most referenced in the American media two weeks following the September 11 attacks because of its terrorist topic.