So Long at the Fair (US re-release title The Black Curse) is a 1950 British thriller film directed by Terence Fisher and Antony Darnborough, and starring Jean Simmons and Dirk Bogarde.

[3] The first published version of the story was written by Nancy Vincent McClelland as "A Mystery of the Paris Exposition" in The Philadelphia Inquirer dated 14 November 1897.

[3] The German author Anselma Heine's novel Die Erscheinung (1912) covers the same idea, and it was filmed as a segment called 'The Apparition" in Unheimliche Geschichten (Uncanny stories) (1919, remake 1932).

Belloc Lowndes' 1913 novel The End of Her Honeymoon also contains the tale,[3] as does Lawrence Rising's 1920 She Who Was Helena Cass, Sir Basil Thomson's 1925 The Vanishing of Mrs. Fraser, and Ernest Hemingway's 1926 The Torrents of Spring.

The title of the novel and film derives from the line, "Johnny's so long at the fair", which can be found in most versions of the nursery rhyme, "Oh Dear!

This is Vicky's first time in Paris, and after checking into the Hotel Lucrèce, she drags her tired brother to dinner and to the famous Moulin Rouge.

When English painter George Hathaway drops off his friend Rhoda O'Donovan and her mother at the hotel where the Bartons are staying, he asks Johnny for change for a 100-franc note to pay a carriage driver.

However, unbeknownst to either party, Rhoda O'Donovan was asked by George Hathaway to deliver a letter containing his loan repayment to Johnny.

When he confirms having met her brother, she bursts into tears, partly in relief since Madame Hervé had been placing Vicky's sanity in doubt.

[5] Fearful that news of a case of plague would be disastrous for the Exposition, Madame Hervé and the doctor whisked Johnny away in secrecy to a rundown Parisian hospital.

George brings Doctor Hart to the hospital, who examines Johnny and tells Vicky her brother has a chance of living.