Lengthy criminal investigations must surely consist of 90 per cent tedium to 10 per cent excitement. TV dramas on the other hand, have to create the converse proportion. In dramatising the five-year investigation into the crimes of John William Cooper, writer Nick Stevens manages to keep the plot taut over three successive nights, while making clear how much grinding routine is involved in the quest for justice.

Prolific local burglar Cooper is the prime suspect in the unsolved 1989 murders of a couple on the coastal path in Pembrokeshire, Wales, and a person of interest in another double murder which took place in 1985. There is also the case of five local teenagers terrorised in a field by a man with a gun, who raped one of the girls.

Hauntingly suggestive evidence links all cases, but it’s not enough. Cooper, in prison for burglary, is being considered for parole. If he really is a serial killer, lead detective Steve Wilkins theorises he is sure to kill again, impelled by “10 years worth of fantasies and compulsions”.

Playing Cooper, Keith Allen practically has “crafty” tattooed on his forehead. As he whiles away time in his cell playing darts and watching TV, Cooper maintains an attitude of disgruntled innocence, discarded when cowed wife Pat (Caroline Berry) comes to visit. She too is dreading his release. But in 2006 the Dyfed-Powys Police have one great advantage over the initial investigators: advances in DNA profiling. Wilkins enlists the help of a local TV journalist to unsettle their suspect, as even in prison “He never misses Wales Tonight”.

The toll the lengthy investigation takes on Wilkins (Luke Evans, looming like an empathetic chunk of granite) is sketched by way of his teenage son’s disgruntlement. “Thanks for being there for me today, Dad!” the boy seethes after yet another parental no-show. Stevens doesn’t labour the cliché, however; the only family life we’re really interested in here is that of the ghastly Coopers, whose treatment of son Andrew (Oliver Ryan) is slowly, awfully revealed.

The cat-and-mouse game continues with a series of tense interviews. Since DNA testing is expensive, the team must go over all the evidence and work out from Cooper’s twitches what’s worth sending to the lab. There’s a crucial eye-witness sketch of a man in buttock-clenching shorts who withdrew money using a victim’s bank card; can the offending garment be tracked down after all these years?

Detective Richards (Alexandria Riley) has the unenviable task of questioning the belligerent Cooper, who has “a very low opinion of female intelligence”. He also has a particularly sinister way of dealing with questions he doesn’t like. Sit back and enjoy the world-class eyeballing.


On ITV, January 11-13 at 9pm

Follow on Twitter to find out about our latest stories first

Listen to our podcast, Culture Call, where FT editors and special guests discuss life and art in the time of coronavirus. Subscribe on Apple, Spotify, or wherever you listen