Fans of schlocky horror movies will be disappointed (or relieved) to learn that The Beast Must Die is not a remake of the 70s movie with the 'werewolf minute' in which viewers were given 60 seconds to guess the human identity of a murderous lycanthrope. Instead, we have to go further back in time for the source material to this five-part drama (the first original series from BritBox), a 1938 novel by Cecil Day-Lewis under the pen-name of Nicholas Blake. His psychological thriller revolves around a crime writer who attempts to concoct the perfect murder in revenge for the death of his son at the hands of a hit-and-run driver.

In this version, the grieving parent is Frances Cairns (Cush Jumbo), a single mother who has relocated temporarily to the Isle of Wight in order to track down the killer herself after discovering that the original police investigation was flawed at best, corrupted at worst. Within a very short period of time, Frances implausibly succeeds in getting a foothold into the plush Rattery home whose patriarch George (Jared Harris) rules the roost with an autocratic fervour. He is, to all intents and purposes, the prime suspect.

For a family with so many secrets to hide, it seems almost unbelievable that they would let a complete stranger through the front door never mind have them hanging out at her own pace, and practically handing their fragile teenage son Phil (Barney Sayburn) over to her care (she is a teacher by profession, but still). As the evidence mounts up towards George being the killer, Frances plots his demise.

Meanwhile, back at police HQ, a new lead detective, the curiously named Nigel Strangeways (Billy Howle), is looking afresh at this mystery while having issues of PTSD from a previous case which leave him suffering brutal panic attacks (especially when he catches sight of a firearm which you'd think would cause a few problems at work), and freaking out at home with music therapy. Howle was last seen as the chainsmoking Dutch civil servant who tracked down a serial killer in The Serpent, and he clearly does a fine line in jittery efficiency.

But the main plaudits of this drama go to Jumbo for a masterclass portrayal of grief in almost all its facets, Harris for turning the sleaze dial way past 11, and Geraldine James who plays George's elder sister Joy with a sneering, callous disregard for almost everyone who is unfortunate enough to enter her orbit. The Beast Must Die is as patchy and flawed as the original police investigation here, but it rises to the surface thanks to powerhouse performances and a closing image that is as beautiful as it is haunting.

BritBox, Thursday 27 May.