GRIEF. It’s a tough thing for anyone to deal with, much less a young boy who has to experience it in slow motion as his beloved mum slips way before his eyes with nothing he can do but curse whatever’s out there for making it so.

How do you visualise that in a fantasy framework? This epic yet intimate tear-jerker answers that call with confidence, imagination and emotional resonance.

Based on Patrick Ness’ hugely successful children’s fantasy novel, we centre on 12-year-old Conor O’Malley (extraordinary, Scottish, relative newcomer Lewis MacDougall, seen in last year’s Pan) who not only has to deal with bullies at his school, but has to go home every day to take care of his terminally ill single mum (Felicity Jones).

One night, Connor encounters a giant mysterious tree monster – brought to life with astonishing mo-cap and the booming yet soothing voice of Liam Neeson – who only awakes at a specific time after midnight; 12:07 to be exact, Connor’s own personal Witching Hour.

The monster helps him navigate his pain and deal with the impending loss of his mum by taking him on a journey of three distinct stories that he must confront head on.

It’s a tough thing to get genuine drama and sweeping fantasy right separately, much less combine them into a cohesive, satisfying whole. Spanish director JA Bayona builds on his experience with familial loss and longing exhibited in the likes of horror-mystery The Orphanage and tsunami drama The Impossible, to create something that feels special and stays with you.

Whether it’s in the small conversations between parent and child over how he’s supposed to cope – “If you need to break things then, by god, you break them” his mother tearfully tells him – or Conor taking revenge on one of his relentless bullies with the titular tree monster roaring at his side, it all rings true with a strong emotional core.

Accompanied by Fernando Velázquez’s multi-layered score, the imaginative visuals are often a sight to behold. The eponymous monster is a marvellous creation; an arresting combination of The BFG, The Iron Giant, Groot and both Gandalf and the Ents from Lord of the Rings, made to feel as real as any of the living, breathing humans in this intimate story. Why? Because that’s the way Connor sees him – wouldn’t we all?

Bayona’s film is closer to that of Guillermo del Toro’s deliciously dark Pan’s Labyrinth than it is to an easily digestible, happy-go-lucky fairytale – it definitely skews towards to the older kid target audience. This complex cinematic bedtime story is an ambitious, deeply affecting piece of filmmaking with its hand on its heart and its imagination working overtime.

FOUR STARS