A young girl faces horrors both real and imagined in this adaptation of the graphic novel by artist JM Ken Niimura and writer Joe Kelly (who also pens the screenplay), which combines the fantastical and the emotional to powerful effect. While comparisons with the similarly-themed A Monster Calls are unavoidable, I Kill Giants has a style and impact all its own.

Here, the focus is on 12-year-old Barbara (Madison Wolfe), who is an outcast both at home, where she feels isolated from her siblings, and at school, where she is the friendless target of the local bully. Barbara spends her time protecting the town against the giants she believes may attack at any moment – a process which includes magic potions and elaborate traps. When she befriends new girl Sophia (Sydney Wade) and comes to the attention of the school counsellor (Zoe Saldana), Barbara's personal demons become apparent.

Danish director Anders Walter won an Oscar for his 2013 short Helium, which dealt with death and loss through the eyes of a child, and he again handles these themes with sensitivity and confidence. Crucially, he ensures that his feature debut maintains a dramatic balance – the real-world issues playing out in Barbara's life never overshadow or undermine the unfaltering belief she has in her giant slaying skills.

And so, as the creatures appear to Barbara, hulking figures looming in the woods, their sharp-edges and shadowy bulk are the genuine stuff of nightmares. And Rasmus Heise's evocative cinematography, which takes in both the wind-swept expanse of the Long Island shore and the dark, claustrophobic interiors of Barbara's school and home, also speaks to the character's dual realities.

But it is star Wolfe, in her first lead role, who really drives the narrative, her exceptional performance running the gamut from fearless warrior to heartbreaking vulnerability as the film reveals itself. Barbara so effectively embodies the rage, pain and bravado of adolescence that it's impossible not to be swept up in her quest, to will her on as she confronts that which scares her. That's the mark of a true hero.

Selected release from Fri 6 Apr.