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The film is based on Arthur Conan Doyle 's second Sherlock Holmes story The Sign of the Four and was made at Ealing Studios .
 Arthur Conan Doyle, Ealing Studios
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Arthur Conan Doyle, Ealing Studios