Children fear the death of their parents above everything else. The idea that one’s protector and guide in the world would be taken away is unbearable to a mind unacquainted with death’s inevitability. This is the subject of Juan Antonio Bayona’s latest film, A Monster Calls, as it has been, in some form, for the other two feature films of his career. Bayona’s first, the excellent horror film, El orfanato, took on the parent’s impending grief at the loss of her child, whereas Bayona’s well-crafted but misbegotten The Impossible saw a family temporarily torn apart by a natural disaster (to say nothing of the other families who did lose everything in that tsunami, which is what the film does).

A Monster Calls is more successful than Bayona’s last outing, partially because it sharpens its focus on fewer characters. Conor (newcomer Lewis MacDougall) is a twelve-year-old boy whose single mother, Lizzie (Felicity Jones) is dying of cancer. He’s also dealing with the reality that he will soon have to move in with his strict grandmother (Sigourney Weaver) because his dad (Toby Kebbell) lives in Los Angeles with his new family. On top of that, Conor is a loner and is bullied at school by a set of nasty boys, so he has a lot on his mind. During his nightly bouts of insomnia, when he isn’t haunted by a recurring nightmare, Conor starts to be approached by a massive tree creature, whom he calls the Monster (voiced by Liam Neeson). Despite the Monster’s tiresome habit of telling ambiguous fairytales, Conor comes to rely on the Monster’s presence for comfort in the face of all the stress in his life.

A Monster Calls gets a few things very right and a few quite wrong. Its primary goal is to blow into epic proportions the grieving process that afflicts a young person who is unequipped to deal with the feelings, and around whom the people are unhelpful. Grandma seems just as unwilling to become Conor’s new caretaker, and Dad is constantly itching to get back home to the United States during his short visit, already resigned to Lizzie’s death even though Conor isn’t. Conor is shown to be quite the talented artist, so it’s not too much of a stretch that the Monster may emerge from his particularly fecund imagination. Creative people tend to find creative ways to channel their feelings of anger and helplessness, a concept that screenwriter Patrick Ness (who also wrote the novel upon which the film is based) captures in a wonderful way. Bayona, with Spielbergian flair, puts the money on the screen with the gnarly and awesomely conceived Monster, in concert with beautifully animated sequences that illustrate the Monster’s stories. A film aimed at a younger audience is ideal ground to tell a blustering allegory, and Bayona’s a great man for the job.

It’s when the film turns back to the real world that things become less interesting. Despite the best efforts of Bayona’s go-to cinematographer, Oscar Faura, the non-fantastical sequences of A Monster Calls are mostly a snooze, hampered by stiff performances by Weaver and a mostly forgettable Jones, who fares better here than in Rogue One, but is once again underserved by a script whose ham-fisted dialogue gives her little to work with. Kebbell, so talented in Dawn of the Planet of the Apes, does what he can with little screen time. MacDougall does an admirable job of carrying the film on his shoulders, doing well in scenes that demand a lot of emotion from the young actor. He also plays well across from the Monster (likely a tennis ball at the end of a stick in front of a green screen), whose voice work from Neeson is exactly what it needs to be. The Monster is an excellent creation, mirroring Conor’s emotional range from excitement to rage to sadness, and Neeson performs the part perfectly.

The parts of the film showing the quotidian are so drab and boring, and the fantastical scenes so wonderful, that you wonder whether Bayona was drifting off behind the camera. I can imagine a version of this movie in which the scenes of ordinary life are excised in favor of a summary, so we can see more of the great interactions between Conor and the Monster. But it’s up to the filmmaker to make a movie that is 100% interesting, and Bayona fails to do that. I can still recommend A Monster Calls because its strengths are so great and far outweigh its flaws. Its flaws are considerable, though, so you may find them harder to forgive.