The Third Man is a 1949 British film directed by Carol Reed and starring Joseph Cotten, Alida Valli, Orson Welles, and Trevor Howard. Many critics rank it as a masterpiece for its atmospheric cinematography, performances, and musical score.
The entire script can be found at the here at the DailyScript.com website. You can also find out more about the Cuckoo Clock
speech here on Wikipedia.