Horror movie night terrors come in all shapes and forms. But for pregnant wife Soo-jin (Jung Yu-mi), it’s her loving husband, Hyun-su (Lee Sun-kyun), who strikes fear in her heart every evening at bedtime. It starts with muttered, vaguely menacing, sleep-slurred sentences and soon graduates to unconscious fridge raids and self-mutilation. Once she gives birth, the sleep-deprived and increasingly agitated Soo-jin starts to fear for the life of her new baby. But this deviously twisty South Korean horror-thriller leaves a teasing question mark over who or what the real threat might be.

It’s an impressive first feature from Jason Yu, who is as adept at wielding the sly observational comedy of the film’s first half as he is at ratcheting up the claustrophobic tension later on. The final one of the picture’s three chapters is the least interesting, departing from the dysfunctional wholesomeness of the early stages and adopting a more generic horror movie palette of deranged reds and sulphurous yellows. Still, it’s an enjoyably grisly good time – a film that puts both power tools and Pomeranians to gleefully suspenseful use.

• In UK and Irish cinemas