It’s a bold move to launch a brand-new original drama slap-bang in the middle of summer, when sport dominates the schedules, viewers are spending more time outdoors, and Britain is basking in scorching sunshine. It’s bolder still when that drama is as relentlessly bleak as The Dark, ITV’s adaptation of GR Halliday’s debut novel, From The Shadows. From its muted colour palette to its windswept Scottish Highland setting, this is a series that seems determined to drain every last ray of warmth from your television screen.

Laura Donnelly stars as DI Monica Kennedy, a stern, uncompromising detective whose manner is as forbidding as the landscape she calls home. The Highlands are beautifully photographed but resolutely unforgiving, providing the perfect backdrop for a mystery that opens with a deeply unsettling image. The immaculate body of an older teenage boy is discovered among the heather, his milky-white skin completely unmarked, lying face down with his hands clasped together and stretched out before him, almost as though he has been ceremonially placed there. It’s an image that lingers long after the opening episode.

Kennedy and her partner, DC Connor Crawford, begin the familiar procedural grind of interviewing suspects and piecing together the victim’s life. It’s quickly established that Kennedy isn’t universally admired throughout the surrounding areas. References to previous investigations and apparent failures crop up repeatedly, hinting at a troubled professional past, while an unnerving subplot involving a young woman apparently intent on taking Kennedy’s daughter away to be with a mysterious “him” suggests her personal life is just as complicated.

Structurally, The Dark is a fairly standard detective drama. Another teenage victim soon appears, killed in the same way, allowing Kennedy and Crawford to soon identify the killer’s chilling pattern: he climbs through bedroom windows, communicates with them via burner phones before he does away with them, strangles his victims and leaves a polished black pebble inside each body. Viewers are also shown something Kennedy and Crawford don’t yet know – the victims are drugged into a locked-in state before they’re murdered, fully conscious but unable to move or cry for help. It recalls the horrifying premise of Mark Billingham’s Sleepyhead.

What lifts The Dark above the procedural crowd are its horror sensibilities (we see windows slowly open during the night, for example) and Kennedy herself. She’s prickly, difficult and far from instantly likeable, but she’s also fiercely competent and very intriguing. After two episodes, the mystery is gripping enough, but it’s Kennedy and the secrets she’s clearly carrying that make you want to keep watching.

Paul Hirons

⭐⭐⭐⭐

Rating: 4 out of 5.

The Dark is broadcast in the UK on ITV1 and ITVX