A masterfully crafted historical thriller by Robert Harris. Set in 1943 during World War II, the novel follows mathematician and codebreaker Tom Jericho, who works at the top-secret British codebreaking center at Bletchley Park. When the German Navy changes its Enigma cipher, Allied shipping faces devastating losses. At the same time, the mysterious disappearance of a female colleague draws Jericho into a dangerous investigation involving espionage, betrayal, and hidden secrets. Combining historical accuracy with gripping suspense, the novel offers an immersive look into one of the most fascinating intelligence operations of the war.