Nightmare Alley is a 1947 film noir starring Tyrone Power and Joan Blondell, and directed by Edmund Goulding. The film is based on the 1946 novel of the same name, written by William Lindsay Gresham.
Power, wishing to expand beyond the romantic and swashbuckler roles that brought him to fame, bought the rights to the novel so he could star as the unsavory lead, "The Great Stanton", a scheming carnival barker. The film premiered in the United States on October 9, 1947, then met with wide release on October 28, 1947, later having six more European releases between November 1947 to May 1954.
To make the film more believable, the producers built a full working carnival on ten acres of the 20th Century Fox back lot. They also hired over 100 sideshow attractions and carnival people to add further authenticity.
As noted on the DVD commentary track by Alain Silver and James Ursini, Nightmare Alley was somewhat unusual among film noir in having top stars, production staff and a relatively large budget. Despite a strong promotion campaign, the film was not a financial success upon its original release, due in part to protests against some of the scandalous content. The film has found acclaim and is regarded as a classic.
(Summary from Wikipedia)