Richard is a 37-year-old mining engineer who recently returned to London from the British colony of Rhodesia. He finds city life dull until a neighbor pulls him into an espionage plot. Adaptable and highly practical, he possesses specialized skills in deciphering codes and utilizing explosives. He approaches danger with a mixture of casual confidence and patriotic responsibility, choosing to handle international threats personally rather than relying entirely on authorities.

Franklin is an American spy originally from Kentucky who possesses a strong personal moral code mixed with paranoia and troubling biases. He operates covertly, utilizing ciphers and disguises to evade his dangerous pursuers. His frantic discoveries about a global assassination plot pull Hannay into the dangerous world of international intrigue.

A ruthless organization of German spies operating covertly within Great Britain. The group functions primarily through three operatives: a cruel young man, a stout man capable of assuming numerous identities, and an older man who serves as their primary intellect. They intend to plunge Europe into war by stealing British naval secrets and orchestrating a high-profile political assassination.

The permanent secretary to the Foreign Office, representing the respectable and secure embodiment of British law and government. Despite his high-ranking bureaucratic position, he is skilled in spy craft and remains approachable to ordinary citizens. He provides vital institutional support while recognizing the value of individual initiative.

A young Scottish man who recently inherited a remote countryside inn from his father. Driven by a deep appreciation for Romantic literature, he longs for excitement and distrusts the mundane routines of his daily life. His imaginative spirit makes him a willing participant when unexpected danger arrives at his door.

A well-meaning aspiring politician seeking election in a rival party's stronghold. He relies heavily on the opinions of his handlers and is desperate for assistance with his upcoming political speeches. Despite his ignorance of international affairs, he proves to be an excellent judge of character with valuable government connections.

A working-class Scottish road repairman who holds anti-establishment views and resents his grueling labor. Wearing large horn spectacles and speaking in a thick dialect, he is naturally trusting and hospitable. He serves as a quiet but crucial source of aid during Hannay's desperate evasion.

A privileged socialite whom Hannay knows from London society. He courts upper-class connections for their wealth and prestige, lacking the physical courage found in more humble citizens. He readily defers to authority figures when faced with conflict.

A prominent Greek politician whose impending visit to London makes him a central figure in European geopolitics. His potential removal from power is viewed as a catalyst that could severely destabilize international relations.

A high-ranking official at Scotland Yard. He represents the formal British police bureaucracy that manages criminal investigations and coordinates with foreign intelligence agencies to clear innocent suspects.

A French representative and intelligence official who meets with British politicians to exchange vital military arrangements. He understands the psychological motivations of spies and provides critical insight into their behavior when the group is compromised.

A Scotland Yard deputy tasked with assisting in the search for a coastal departure point used by enemy agents. He is highly capable and possesses the specialized knowledge needed to contact British naval forces docked off the coast.

A working-class London tradesman who unknowingly plays an important role in an espionage escape. Trusting and cooperative, he agrees to a strange request to trade clothing for the sake of what he believes is a sporting bet.