Warner Bros. is being sued for a whopping $900 million dollars, but they can skate free if they just do one small thing: prove that ghosts exist.

How did a major Hollywood studio get caught up in this? Well it's a long story. Do you remember The Conjuring movies? There's been two of them, and a spin-off movie Annabelle. The horror films follow a husband/wife team of paranormal investigators and explore the scary cases they work on.

Both Conjuring movies and Annabelle proclaim that they are "Based on the true case files of The Warrens" meaning Ed and Loraine Warren. They were real-life investigators who made a living "exorcising" ghosts, demons etc.

A book called The Demonologist by Gerald Brittle was written in 1980 exploring their lives. It's because of this book that Warner Bros. is in court.

Brittle signed a contract with the Warrens that guaranteed him the rights to their story. That means no other books, shows or movies can be done without his involvement. However in 1997 Warner Bros. approached The Warrens and purchased these exact same rights without involving Brittle.

In 2015, just before the release of the 2nd Conjuring movie, Brittle sent a cease and desist letter to Warner Bros. claiming that he had sole rights to the story. They responded saying the movies weren't based on The Demonologist and were instead based on "historical facts".

The author has now sued Warner Bros. for $900 million, which is just a few million more than all 3 movies have earned at the box office. He claims that Warner Bros. can't be using historical facts because ghosts and witches aren't real - therefore they must be relying on The Demonologist.

That's why Warner Bros. might have to prove the ghosts exist in order to avoid a hefty pay day.