Holly Martins (Joseph Cotton) is an American novelist. He writes pulp fiction westerns. He has traveled to post war Vienna to see his old friend Harry Lime (Orson Welles). Holly is broke and has been promised a job. When he gets to his friend’s apartment he learns from the apartment superintendent Karl (Paul Horbiger) that Harry died. He was hit by a car crossing the street in front of the apartment building. The funeral is today. Holly heads for the cemetery.

At the grave site are several people. Among them are Major Calloway (Trevor Howard) from the British Royal Military Police and his assistant Sergeant Paine (Bernard Lee). Calloway gives Holly a ride back to town. He takes Holly to a local pub and buys him a few drinks all the while subtly questioning him. Calloway has never heard of the author but Paine is a fan of Holly’s pulp westerns. Calloway informs Holly that his friend Harry was into selling stuff on the black-market. Specifically watered down penicillin. Holly gets drunk so Calloway has Paine drop him off at a hotel for the night with enough pocket money to send him back to the states in the morning.

At the hotel Holly receives a call from Baron Kurtz (Ernst Deutsch) who says he was a friend of Harry as well. He meets with the Baron who tells him he was one of the two people who carried Harry to the curb after he was hit. He says the other was a man named Popescu (Siegfried Breuer). Holly wants to talk to him but the Baron says he has left Vienna. Holly asks about two other people he saw at the funeral, a man and a woman. The Baron explains that one was Harry’s doctor, Dr. Winkel (Erich Ponto), and the other was Harry’s girlfriend, an actress named Anna Schmidt (Alida Valli).

After talking to Anna and Winkel Holly checks out the spot where the accident happened. He then talks to Karl again who tells him there were actually three men that moved Harry to the curb. A third man is something that is disputed by the Baron and Harry’s doctor. Then Karl is murdered. Holly is now beginning to believe that Harry’s death was not an accident. Holly wants Harry’s death investigated but there’s a lot more going on here then even Holly imagines.

“The Third Man” was released in 1949 and was directed by Carol Reed. It is a British mystery thriller and a film noir. The movie is classic noir, yet it’s not. It has all the main elements of noir, the night, the wet payment, the lighting, the angles, trench coats, fedoras, smoking, I could go on. Yet, the choice of music score was an elevation that took the movie to a different level. The composer of the film’s score is Anton Karas, an Austrian musician. Director Carol Reed heard him play the zither and liked the sound the instrument made. Basically all of the music for the film is just the zither. "The Third Man Theme" spent eleven weeks at number one on Billboard's US Best Sellers chart. The music from the film became so popular that if often pops up in other movies from time to time.

A lot of the film's action takes place in the sewer system. There is a special unit attached the Vienna Police Dept that is assigned solely to patrol the city's intricate sewer system. The system is a network of interlocking tunnels that are quite tempting to the criminal element. Off duty members of this unit were used as extras playing police officers in the sewer scenes.

Orson Welles refused to film any of the scenes in the Vienna sewers. He was convinced that the bad air would give him some kind of disease. Director Reed tried to assure him that the smell was disinfectant and not sewage but Welles wasn’t convinced. For close-ups sets duplicating the sewer were constructed on sound stages back in England. For long shots a body double was used. Reportedly the resulting footage is about 85% Vienna and 15% London. Welles wrote his own dialogue and the scene where his fingers come through the grill was his idea but since he wasn’t in Vienna at the time the fingers belonged to Carol Reed.

The giant Ferris wheel that Martins and Lime ride on in the Prater Amusement Park was erected in 1897. Sigmund Freud claimed to have used it to induce seasickness in patients while experimenting with cocaine as a treatment.