Writer-director Dennis Bartok’s mildly diverting debut horror film is a cheerfully derivative exercise in jump scares, dark shadows and low-budget-driven aesthetics. In Dublin, hyper-fit athletics coach Dana (Shauna Macdonald) is hit by a car while out running. She wakes up with a respirator in her throat and serious injuries in a spooky hospital that hardly seems to have any patients, even though her nurse, Trevor (comedian Ross Noble), complains bitterly about being overworked.

As Dana slowly recovers and learns to use a laptop to communicate with her caregivers, husband (Steve Wall), and teen daughter (Leah McNamara), she learns about the hospital’s hideous secret: years ago, a nurse there killed children, died and then seemingly transmogrified into a variant on internet-meme-turned-urban-myth Slender Man, judging by his gaunt appearance and long, unmanicured fingernails (hence the title). With its creepy music and only-just-adequate performances, this will serve nicely at future slumber parties for thrill-seeking tweens.