'The Third Man' (1949) by Graham Greene

Set in post-World War II Vienna, a city divided into four zones controlled by the Allies (Britain, France, the United States, and the Soviet Union), The Third Man follows Rollo Martins, a struggling writer of pulp Westerns, who arrives in the city to meet his old friend Harry Lime. Upon arrival, Martins discovers that Lime has recently died in a suspicious car accident.

Curious about the circumstances of Lime’s death, Martins begins investigating and soon realizes that the official story doesn’t add up. Witnesses mention the presence of a mysterious "third man" at the scene who is unaccounted for. As Martins digs deeper, he uncovers that Harry Lime was involved in a black-market operation selling diluted penicillin, which caused the deaths and suffering of many, including children.

Martins also becomes entangled with Anna Schmidt, Lime’s lover, who remains loyal to Harry despite learning the truth. The British military officer Major Calloway urges Martins to abandon his romanticized view of Lime and see him for the criminal he truly was.

The novel builds toward a dramatic confrontation in Vienna’s underground sewer system, where Martins is forced to confront both the reality of his friend’s crimes and his own moral responsibility. In the end, Harry Lime is killed, leaving Martins disillusioned and Anna refusing to forgive or follow him.

The story explores themes of betrayal, moral ambiguity, and the corrupting effects of post-war survival. It reflects the tension between personal loyalty and the demands of justice in a broken, war-torn world.