The movie is headed towards an early July start with a script by Boone and his writing partner, Knate Lee. Simon Kinberg and Karen Rosenfelt are producing.

New Mutants, created by Chris Claremont and Bob McLeod, was the first X-Men comic spinoff, launched in the early 1980s as the franchise began two decades of dominating the comic book industry.

The pic will focus on the angst-driven adventures of a diverse group of teens that include Native American Danielle Moonstar, Scots girl Wolfsbane, Brazilian ladies man Sunspot, a Kentuckian code-named Cannonball and Russian teen Magik. Also in the mix will be an alien named Warlock.

Taylor-Joy will play Magik, a girl who has learned sorcery and uses teleportation discs to travel. She is also the sister of Colossus, an X-Man who appeared in Deadpool.

Williams will play Wolfsbane, a girl struggling to reconcile her religious beliefs with her power to turn into a wolf.

Boone has been eyeing the actresses since last year but was only able pull the trigger on them once the movie was greenlighted earlier this year. New Mutants has a release date of April 13, 2018.

Fox is making serious efforts to find ethnically appropriate actors, conducting wide searches for a Native American to play Moonstar and a South American for Sunspot.

Taylor-Joy broke out with the 2015 award-winning period horror movie The Witch and starred with James McAvoy in M. Night Shyamalan’s surprise hit Split. She is repped by CAA, Felker Toczek and Troika in the U.K.

Williams plays Arya Stark on HBO's Game of Thrones, which launches its seventh season in July. She is repped by WME, Jackoway Tyerman and the U.K.'s Louise Johnston Management.