A widowed father (Aneurin Barnard) trapped in a deserted Glasgow sink estate by chronic agoraphobia finds he's at the mercy of a vicious gang of shadowy feral kids intent on grabbing his infant daughter. Seeking help from a fiery priest (James Cosmo), he has to battle his fear of the outdoors as well as the mutant thugs. Irish writer-director Ciaran Foy's impressive 'hoodie horror' skilfully sidesteps the genre cliches to deliver a bleakly terrifying tale of a father willing to risk everything for his child.
Proud dad-to-be and dutiful hubbie Tommy Cowley (Barnard, excellent) thinks life is on the up when he prepares to move out of his grim Glasgow high-rise with his pregnant wife.
However, on the day of the move, he find himself trapped in a knackered lift staring horrified through the greasy window as a sinister trio of hooded children monster his wife in the corridor outside and plunge a dirty syringe into her stomach.
Fast-forward nine months and he's the father of a baby girl, but his wife remains in coma following the attack and he's developed an extreme agoraphobia which confines him and his kid to a flimsy house on a condemned sink estate.
And then it starts. The killers - spectral yobs who drift silently past the window before violently breaking down his door and streaking through the house at will - begin to zero in on their victim and Tommy realises they're after his child.
Support comes from kindly nurse Marie (Mosaku) and Tommy also seeks help from local priest James Cosmo, a militant firebrand who has very radical proposals for dealing with the marauding youth.
Director Ciaran Foy - who found himself housebound following an attack - has constructed a lean and mean horror set in a shattered city that is both all-too-recognisable as broken Britain while also feeling totally alien.
Barnard impresses as the shellshocked Tommy, crippled by his condition, yet drawing the strength from his unconditional love for his daughter to confront his barely human nemeses.
Until the final reel, when there's a half-hearted explanation for the feral delinquents, their presence is chillingly evoked, from sinister reflections in kettles and car doors to a solid menace distorted by frosted glass.
It will be interesting to see what Foy does next.