Every Christmas season, there’s at least one film that rumbles into theaters with the sole purpose of yanking tears from its most cold-hearted viewers. Enter A Monster Calls, a story about a young boy wrestling with his mother’s terminal illness. In a way, the film succeeds; it’s hard not to get choked up at a premise like that. But as the movie rumbled toward its inevitably devastating conclusion, the chief emotion I felt wasn’t sadness but annoyance at the dashed grander potential.

A Monster Calls is a visually inventive piece of magical realism that sets out to unravel the cloying narratives people often weave around their own grief. It mixes the intimate sorrow of 12-year-old Connor (Lewis MacDougall), whose mother Lizzie (Felicity Jones) is dying, with the painterly CGI extravaganza of a titanic tree monster (voiced by Liam Neeson) who visits Connor in the night to tell him strange folk stories. Directed by J.A. Bayona (the Spanish filmmaker behind the artful horror movie The Orphanage and the overwrought disaster epic The Impossible), A Monster Calls is at once trying to subvert children’s fairytales and become a classic in that genre. But it ends up succeeding at neither goal, instead leaning on obvious, manipulative storytelling tactics to ineptly tie its two narratives together.

Bayona’s The Orphanage was a fine haunted-house movie, and A Monster Calls could honestly benefit from more subtle menace, given that its best moments are its most quiet. As his mother spends much of her time in the hospital, Connor moves to his grandmother’s manse, which is creepily decorated with porcelain dolls and not-to-be-touched antiques. Bayona conjures something gently unsettling from Connor’s life with his stuffy grandma (played, with a regrettable English accent, by Sigourney Weaver), but whatever nuance he might be aiming for is quickly dispensed with when a giant tree monster rips off Connor’s bedroom wall and starts talking to him.

The dynamic between Connor and the monster is simple: The monster says he will tell Connor three stories and then will want a story in return. Neeson lends his gravelly Irish brogue to the creature, but these scenes feel disappointingly weightless otherwise. The monster might roar, grab Connor with his spindly limbs, or even smash property around him, but his emotional impact is negligible, and his purpose in Connor’s life is kept shrouded in mystery for too long.

Their relationship is openly antagonistic for most of the film. Connor doesn’t understand why the monster keeps bothering him at night, since all he wants is help for his mother. The monster’s repeated mentions that he will eventually need “a story” from Connor ultimately make the purpose of their encounters depressingly clear: This creature of the subconscious is trying to get Connor to realize, and acknowledge, some dark truths. Over the film’s 108-minute running time, Connor and the monster bark the same demands at each other, to little avail. It’s no surprise A Monster Calls is based on a children’s book: The narrative is so simplified the movie exhausts itself trying to keep a minimum level of momentum until its conclusion.

Outside of his relationship with his mother, viewers get very little sense of what Connor is like as a person. A schoolyard bully repeatedly taunts him for having his head in the clouds, which seems implausibly cruel even by the standard of 12-year-old boys, given that his mother’s illness is public knowledge. The oppressive dreariness of Connor’s real life might work if it were balanced against something more fantastic, but the monster’s scenes are bland and devoid of humor or childlike wonder.

Bayona’s visual sense does come to life in depicting the monster’s fables. Each one is a warped version of a bedtime story, where the heroes and villains seem indistinguishable (Connor’s frustration with his colossal companion comes in part from his disappointment with the tales). Though their purpose to the larger narrative is vague, the stories—rendered in vivid, eerie watercolors—are the most arresting part of the movie. When Connor’s “story” finally arrives, however, in the form of a terrible nightmare, it’s drawn-out and far too reliant on crummy CGI, lacking both the magic of the animated sequences and the heartbreaking fact of his mother’s illness.

The ending still hits home—of course it does, given the upsetting subject matter and the skill of the actors involved (MacDougall makes for a fine young foil to Jones and Weaver). But it’s a poignant blow that the movie doesn’t come close to earning. A Monster Calls is a tear-jerking mishmash, a collision of high fantasy and sobering reality that can’t build its disparate elements into something greater. If you’re looking for a good holiday cry, it’ll likely do the trick; but you may walk out of the theater feeling that its emotional gut-punch was more of a sucker punch.