Maurice Castle is a high-level operative in the British secret service during the Cold War. He is deeply in love with his African wife, who escaped apartheid South Africa with the help of his communist friend. Despite his misgivings, Castle decides to act as a double agent, passing information to the Soviets to help his in-laws in South Africa. In order to evade detection, he allows his assistant to be wrongly identified as the source of the leaks. But when suspicions remain, Castle is forced to make an even more excruciating sacrifice to save himself. Originally published in 1978, The Human Factor is an exciting novel of espionage drawn from Greene’s own experiences in MI6 during World War II, and ultimately a deeply humanistic examination of the very nature of loyalty. This edition features a new introduction by Colm Tóibín. For more than seventy years, Penguin has been the leading publisher of classic literature in the English-speaking world. With more than 1,700 titles, Penguin Classics represents a global bookshelf of the best works throughout history and across genres and disciplines. Readers trust the series to provide authoritative texts enhanced by introductions and notes by distinguished scholars and contemporary authors, as well as up-to-date translations by award-winning translators.