Holly Martins, an American writer of bad cowboy stories, arrived in Vienna one very cold February morning. It was soon after the Second World War; Vienna was in ruins and was occupied by the Americans, Russians, British and French. Holly Martins had been invited to Vienna by an old friend, Harry Lime, and so he was surprised thatHarry was not there to meet him. When Holly went to flat, he found out that his friend had been killed by a truck ashe was crossing the street outside his flat.
In fact, the funeral was taking place that afternoon so Holly went straight to the cemetery. There were very few people there. A beautiful dark-haired woman was the only person among them who looked upset. After the funeral, Major Calloway, a British military policeman, told Holly that his friend Harry had been a criminal but Holly did not believe him. Back at his hotel, Holly met a man who mistook him for a famous American novelist and asked him to give a lecture. Holly accepted, as this would give him a chance to stay in Vienna for few days and find out what had happened to Harry.
The next day, holly began his search, he first met an Austrian friend of Harry's called Kurtz. Kurtz described how he and another man, Popescu, had carried Harry's body to square after the accident. Before he died, Harry had asked Kurtz to look after Holly. This surprised Holly because Calloway had told him that Harry's death had been very sudden. Holly asked Kurtz about the woman at the cemetery. She was Harry's girlfriend, Anna Schmidt, an actress.
That evening, Holly met Anna and she told him more about the accident. Harry's doctor, Dr Winkel, had been passing and had certified the death. The driver of the truck had been Harry's own driver. In fact, there had been no strangers there at all. Holly began to think that it might not have been an accident. The porter of Harry's flat then gave Anna and Holly another version. Harry had died immediately and three men had carried the body. So who was this mysterious 'third man'?
When they got back to Anna's flat, Calloway was there and arrested Anna because her paper were forged. Holly told Calloway what he had learnt about Harry's death but Calloway told him to leave death to the professionals' and go home. However, Holly was determined to find out the truth. He talked to Dr Winkel and to Popescu, Harry's Rumanian friend. Popescu denied that there had been a 'third man'.
When Holly went back to scene of the accident, the porter said, 'I'd like to tell you something ..... tonight.' But when he and Anna went to see the porter that night, they found that he had been murdered. The porter's son accused Holly of being the murderer. Anna and Holly had to escape and hide in a cinema. Holly finally got back to his hotel to find a taxi waiting to take him to his Wednesday evening lecture.
Holly's lecture was so terrible that most people walked out but Popescu was there. He asked Holly questions about his new 'novel9. Holly said it was a 'murder story', it was 'based on fact' and was called 'The Third Man'. There were two other men with Popescu so after the lecture, Holly ran out of the room. He managed to escape a second time and went to police headquarters. Calloway told Holly in detail about his friend Harry's crimes. He had sold diluted penicillin that had caused the deaths of thousands of innocent victims, especially children. Holly was finally convinced and decides to leave Vienna.
He went to see Anna to say goodbye and saw a man standing in a door on the other side of the street. It was Harry Lime! He called out but Harry mysteriously disappeared. Holly rang Calloway and they realised that Harry had escaped underground into Vienna's sewers. Holly spoke to Kurtz and Winkel and told them to organise a meeting with Harry. The two friends met at last on the big wheel in the Prater amusement park. Harry showed no regret for the crimes he had committed and even threatened to kill Holly. After that, Holly agreed to help Calloway catch Harry.
Holly arranged to meet in a cafe whicf Calloway and his men had surrounded. Anna came in and tried to warn Harry but it was too late. Harry pulled out his gun to kill Holly but the police came in. Harry escaped and disappeared underground. Calloway, his men and Holly followed him into the sewers where there were shots. Cornered like a rat and badly wounded, Harry tried to go up a ladder out of the sewer. Holly saw his friend and went after him. Calloway shouted:'Martins. If you see him, shoot.' Harry looked at his friend and nodded. Holly pressed the trigger.
Before he left Vienna, Holy went to his friend's second funeral. There were even fewer people than at the first funeral. Afterwards, Holly tried to talk to Anna but she ignored him and walked away.