Richard Hannay, a well-to-do retired mining engineer. Wishing to protect himself from Scudder’s murderers and to relay to proper authorities Scudder’s secret coded information (in a small black book), Hannay escapes to Scotland to hide but at the same time gives the impression that he killed Scudder. He evades the pursuing Black Stone and the police, as well as decoding Scudder’s book; by doing so, he learns of invasion plans against England and informs Sir Walter. Revealing the imposture of the false First Lord of the Admiralty and finally discovering the meaning of the thirty-nine steps, Hannay is able to bring about the capture of the Black Stone.
Franklin Scudder, an American, a private investigator fearful of being murdered because of his knowledge of the Black Stone’s plans. During Hannay’s absence, Scudder is stabbed to death in Hannay’s flat.
Sir Walter Bullivant
Sir Walter Bullivant, a government official who at first is skeptical of Hannay’s information; he is convinced upon learning of Karolides’ death. He passes on Hannay’s warning to other government officials.
The Black Stone
The Black Stone, a group of espionage agents who kill Scudder and Karolides and attempt to prepare for a German invasion of England. They are captured just before escaping from England in a fast yacht.
Constantine Karolides, a Greek diplomat assassinated by the Black Stone.
Sir Harry, a newfound friend of Hannay and godson of Sir Walter.