Sigourney Weaver has signed on to star in the fantasy adaptation A Monster Calls, joining Felicity Jones and Liam Neeson.

The story centers on a young boy, who gets bullied every day at school and has to deal with his mother's terminal illness at home. He escapes into his own fantasy world, where he is guided by a tree monster who tells him various stories. Sigourney Weaver is playing the boy's grandmother, while Felicity Jones is playing his mother and Liam Neeson is portraying the tree monster.

Juan Antonio Bayona (The Orphanage, The Impossible) is directing from an adapted screenplay by Patrick Ness, based off his own award-winning children's fantasy novel. River Road's Bill Pohlad and Mitch Horwits are executive producing alongside Participant's Jeff Skoll, Jonathan King, and Lionsgate Motion Picture Group co-chairman Patrick Wachsberger. No production schedule was given at this time.

Related: Fantastic Four Star Toby Kebbell Joins A Monster Calls

Sigourney Weaver, who reportedly just turned down a role in The Expendables spin-off ExpendaBelles, will next be seen in Exodus: Gods and Kings and Chappie.