Before Edward Snowden's infamous data breach, the largest theft of government secrets was committed by an ingenious traitor whose intricate espionage scheme and complex system of coded messages were made even more baffling by his apparent dyslexia. In this fast-paced, true-life spy thriller, Yudhijit Bhattacharjee reveals how the FBI unravelled Brian Regan's strange web of codes to build a case against a man who nearly collapsed America's military security.