Rooting about in a grieving ’tween’s subconscious in ‘A Monster Calls’

Lewis MacDougall, as Conor, with The Monster (performed and voiced by Liam Neeson) in “A Monster Calls.”Focus Features

The onscreen depiction of grief has been well-trodden conversational territory recently, thanks to Casey Affleck’s acclaimed, heavily internalized performance in “Manchester by the Sea.” Audiences get another challenging meditation on the subject in “A Monster Calls,” this time from the perspective of a psychologically suffering ’tween. The film is a semi-fantastical drama dotted with splashy visual effects, notably a Liam Neeson-voiced anthropomorphic tree that stalks the young protagonist’s dreams and subconscious. But anyone assuming that this comparably overt portrait of anguish lacks a certain emotional complexity is in for a surprise.

Lewis MacDougall (“Pan”) is Conor, a 12-year-old, artistically inclined British boy whose serious demeanor is one of the few clues about the ordeal he’s quietly enduring at home. Conor’s adoring single mum (Felicity Jones) is clearly faring poorly in a cancer fight, no matter how much mother and son might assure each other that she’s about to turn a corner. A difficult time is made tougher by bullying Conor faces at school. There’s also the arrival of his expat dad (Toby Kebbell), and the interventions of his grandma (Sigourney Weaver), whose prickly pragmatism has never been very welcome.

Then things get really heavy: Amid all the tumult, an enormous, spooky tree in the graveyard outside Conor’s window comes to volatile, molten life, cryptically rambling about how it intends to swap some stories with him. (Neeson’s creature might make genre fans flash back to Tolkien and “The Two Towers,” but Groot spliced with Optimus Prime and Jacob Marley also works.) These folktales-within-the-tale are rendered in brooding watercolor animation that mirrors Conor’s worldview, and characterized by a moral randomness consistent with his experience.

Who knows why such bad things happen in these narratives? They just do. It’s a confounding realization that bleeds into Conor’s waking life in striking ways.

Parents of grade schoolers be warned: This is not “The BFG.” Kids younger than MacDougall is playing could have trouble with the movie’s themes and intensity.

Director J.A. Bayona (“The Impossible”) again ambitiously examines the mind-set of a boy struggling with adult-size burdens, and he’s got perfect material to work from in the insightful script by source novelist Patrick Ness. Jones lends weight to a sickly and sympathetic assignment that doesn’t give her half as much opportunity for nuance as “Rogue One,” while Weaver is an unexpectedly effective casting pick as a granny and a Brit.

But MacDougall, fittingly, leaves the biggest mark. In a moviegoing season that has trained a spotlight on tamped-down emotion, he’s impressively stifled in his own right. “A Monster Calls” is a portrait of coping that’s both fascinating and heartbreaking.

★ ★ ★
A MONSTER CALLS

Directed by J.A. Bayona. Written by Patrick Ness, based upon his novel and an idea by Siobhan Dowd. Starring Lewis MacDougall, Felicity Jones, Sigourney Weaver, Liam Neeson. At Boston Common, suburbs. 108 minutes. PG-13 (thematic content, some scary images).