Secret of the Sphinx (Italian: La sfinge sorride prima di morire – Stop Londra) is a 1964 film, directed by Duccio Tessari, which stars Tony Russel, Salah Zulfikar, Maria Perschy, Ivan Desny, and Manuela Kent.
Thomas and Hélène meet in Cairo as a Lloyd's of London agent investigates an Egyptian bank robbery.
The agent suspects that the band of robbers is hiding among the archaeologists who are carrying out the excavations and, in fact, when the expedition returns to Cairo, he discovers that the chests contain the gold stolen from the bank.
Tony Russel liked the script and especially the idea of going to Egypt and he accepted the job by turning down the lead in A Fistful of Dollars.
In the United States it was released on DVD and VHS in 2004 by "Something Weird Video" (SWV) under the title Secret of the Sphinx.