Patrick Ness’ children’s fantasy novel A Monster Calls is a sad story with an even sadder story behind it. The protagonist is a 13 year-old boy called Conor whose mother is suffering from terminal cancer. After experiencing the same nightmare over and over for months, Conor wakes up one night to find a monster made out of leaves and branches at his bedroom window, who promises to help him by telling him three stories.

The idea was conceived by writer Siobhan Dowd while she was suffering from breast cancer, though she passed away before she was able to write it down. Patrick Ness turned the idea into a novel, then later adapted the novel for the screen. The script has since made it onto the Hollywood Black List, and now plans are in place to get A Monster Calls into production.

Spanish director Juan Antonio Bayona, who is best known for his chilling ghost drama The Orphanage, has now signed on to direct A Monster Calls. River Road Entertainment, Participant Media, Lionsgate International, and Focus Features are teaming up to finance and distribute the film, which is set for a fall 2016 release.

Bayona’s most recent film was The Impossible, a drama about a tourist family who are caught up in the 2004 Indian Ocean tsunami while visiting Thailand and struggle to survive and reunite in the aftermath. The film won five Goya awards and lead actor Naomi Watts received an Oscar nomination for her role.

Now that Bayona is committed to A Monster Calls, there’s a strong likelihood that his upcoming sequel to World War Z won’t arrive in theaters until around 2017. Examiner reports that A Monster Calls is set to begin filming in September, and since the World War Z sequel doesn’t even have a screenwriter yet, let alone a script, it will probably have to wait until production is complete on A Monster Calls.

In concept A Monster Calls sounds like it could have some strong similarities to Pan’s Labyrinth and Where the Wild Things Are, with a young protagonist seeking to escape from his troubles through fantasy and stories. It will be interesting to see what a director like Bayona does with the material.

A Monster Calls is expected to release in fall 2016.