Gravity benefited strongly from the Chinese love of 3D and Imax. It was pitted head to head with The Hunger Games: Catching Fire at the Chinese box office as the two Hollywood epics opened almost simultaneously, but it grossed inearly three times as much, largely because it had double the number of screenings. It's average ticket price of $6.70 was also higher than the Hunger Games sequel's $5.20.

Best-selling author Tess Gerritsen is suing Warner Bros. with the allegation that its blockbuster film, Gravity, is derived from her 1999 book by the same name.

The complaint filed in California federal court on Tuesday doesn't allege copyright infringement. Instead, it's a contract claim stemming from a film option she sold when the book was released. Gerritsen's book is described as featuring "a female medical doctor/astronaut who is stranded alone aboard a space station after a series of disasters kill the rest of the crew."

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A company called Katja picked up film rights to her Gravity book for $1 million. Additionally, she was promised that if a film "based on" her book was made, she would receive a $500,000 production bonus, screen credit and, maybe most importantly, 2.5 percent of defined net proceeds. Last year's film -- which won seven Oscars -- grossed more than $700 million worldwide, putting potentially a lot at stake in the new lawsuit.

Gerritsen is making a breach of written contract claim, meaning that she thinks that she can prove that Warner Bros. holds obligations to her directly. The basis for this assertion is that Katja was allegedly a wholly-owned subsidiary of New Line when it optioned her book, and that New Line was later sold to Warner Bros.

Because this isn't a copyright claim, the degree of similarity between the 1999 book and last year's film is less important than usual. Still, if she hopes to win millions, she'll at least need to demonstrate that the movie was "based on" what she wrote. Otherwise, the contract doesn't apply.

In a statement announcing the lawsuit, Gerritsen said she originally believed that another film storyteller had independently come up with similar elements to her book. (She has given interviews in the past where she denied that credit be given to her, so she may be acknowledging this to explain away such past statements.) But then she says she received "startling new information" that someone involved in her project when it was in development was also involved in the blockbuster film.

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She doesn't say more, but in the complaint, it is alleged that Gravity director "Alfonso Cuaron was attached to the Gerritsen Gravity Project and worked on developing the Book into a Picture. Gerritsen was not told of this attachment at the time."

Gerritsen and her attorney, Glen Kulik, will be attempting to show that all this amounts to way too much coincidence. In the lawsuit, she is seeking at least $10 million in damages.

Warner Bros. has not publicly commented on the matter.

Email: Eriq.Gardner@THR.com

Twitter: @eriqgardner