In 2014, the family lost rights to the majority of Conan Doyle’s works after a judge ruled that any Holmes story written before 1923 were in the public domain.
However, they now claim that Enola Holmes borrows elements from the final 10 stories, which were written between 1923 and 1927.
A lawsuit has been filed against the streaming service, Legendary Pictures, Penguin Random House, Springer, Thorne and director Harry Bradbeer.
It claims the “copyright infringement arises from defendants unauthorised copying of original creative expression by [Conan Doyle] in copyrighted Sherlock Holmes stories”.
The suit also claims that Enola Holmes incorporates the “human connection and empathy” that were only displayed by the detective in the copyrighted books.
It suggests that Conan Doyle wrote Holmes differently following the death of his eldest son and brother in the First World War.
The Independent has contacted Netflix, Legendary and Thorne for comment.
Henry Cavill, Helena Bonham Carter, Sam Claflin, Fiona Shaw and Adeel Akhtar also star in the film, which will be released on Netflix later this year.
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