Witherspoon received various awards for producing the 2014 film "Gone Girl".
A screenplay writer named Leslie Weller has claimed she wrote a screenplay called "Out of the Blue" back in 2005 and sent a copy of the same to a script consultant. That allowed someone to lift her work.
She says the book "Gone Girl", which came out in 2012, is a rip off of her screenplay, reports tmz.com.
Mentioning similarities between the book and her screenplay, Weller said they both focus on a married couple's relationship where the husband and wife are slowly drifting apart.
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"They both contain a key twist where the wife is not the nice, normal, and somewhat naive housewife and is in fact a psychopath who sets up her husband," she said.
Besides Witherspoon, Weller is also suing the book's author Gillian Flynn and the movie's director David Fincher.