Patrick Ness's heartbreakingly beautiful novel A Monster Calls is getting the big-screen treatment. Focus Features released the official trailer for the film (which Ness also wrote) on Wednesday (July 13), and oh man is it ever going to make you bawl your eyes out.

The film tells the story of 12-year-old Conor (Lewis MacDougall) who tries to balance his mother's (Felicity Jones) terminal illness, bullies picking on him at school, an absentee father (Toby Kebbell), and an inhospitable grandmother (Sigourney Weaver), all with a ginormous monster who wants Conor to tell the truth about what secret he's hiding. Liam Neeson voices the Monster and tells Conor, "I know everything about you, the truth that you hide."

Check out the trailer below.

A Monster Calls premieres in theaters October 21, 2016.