Lionsgate announced today that it has acquired the feature film rights to Danielle Vega's horror novel The Merciless, inspired by real events, set for publication on June 12, 2014 by Razorbill Books. Pretty Little Liars creator Marlene King will adapt the novel and serve as an executive producer on the film. Leslie Morgenstein, President of Alloy Entertainment, and Elysa Dutton, Vice President of Alloy Features, will produce.

The Merciless is a story of good girls gone evil. The new girl at a small-town high school is taken in by the popular clique, only to have them compel her into joining them in a dangerous exorcism of a punky, rebellious classmate.

Here's what Erik Feig, Co-President of Lionsgate Motion Picture Group, had to say in a statement.

"Like everyone, we are big-time Pretty Little Liars fans; and like everyone, we can't wait to see Marlene writing about teen girls exorcising the devil out of other teen girls!"

Producer Leslie Morgenstein had this to say in a statement.

"We know we have something special with this project that'll entertain, shock and make audiences rethink what evil truly means. Working with Marlene on the film is exciting because it continues a great relationship that started with our work together on Pretty Little Liars."

Marlene King had this to say in her statement.

"I've had a great time collaborating with Leslie Morgenstein and Alloy on Pretty Little Liars and have enjoyed the thrill of scaring millions of teenagers every week. I intend to be merciless with the script and hope our audience will need to sleep with their lights on after seeing the movie."

Feig is overseeing the project for the studio along with Gillian Bohrer, Lionsgate's EVP of Production & Development, and Jina Jones, Lionsgate's Director of Development.