The Thirty-Nine Steps
by John Buchan | 
The Night Manager
by John le Carre | 
Single & Single
by John le Carre | 
The Spy Who Came In from the Cold
by John le Carre | 
The Secret Pilgrim
by John le Carre | 
Smiley's People
by John le Carre | 
Our Game
by John le Carre | 
A Small Town in Germany
by John le Carre | 
The Tailor of Panama
by John le Carre | 
A Perfect Spy
by John le Carre | 
Absolute Friends
by John le Carre | 
Call for the Dead
by John le Carre | 
Greenmantle
by John Buchan | 
Tinker, Tailor, Soldier, Spy
by John le Carre | 
The Russia House
by John le Carre | 
The Secret Agent
by Joseph Conrad | 
Enigma
by Robert Harris | 
The Human Factor
by Graham Greene | 
Eye of the Needle
by Ken Follett | 
The Great Train Robbery
by Michael Crichton |
While on a sailing trip in the Baltic Sea, two young adventurers-turned-spies uncover a secret German plot to invade England. Written by Childers-who served in the Royal Navy during World War I-as a wake-up call to the British government to attend to its North Sea defenses, The Riddle of the Sands accomplished that task and has been considered a classic of espionage literature ever since, praised as much for its nautical action as for its suspenseful spycraft.