Between the final episode of Doctor Who for at least a year and the return – possibly for the final time – of Idris Elba's DCI John Luther for the first of a four-part, nightly fifth season, New Year's Day is the new Christmas on BBC One. Sadly we aren't allowed to see Who before transmission, but if there are rumours of a return for the Daleks, then there have also been extremely heavy hints that Luther's own recurring nemesis/companion – Ruth Wilson's psychopathic Alice Morgan, whose death Luther investigated in 2015's brief fourth season – will also be back.

What we can say is that this opening episode and its central mysteries have nothing to do with her. As ever, one of the most loveable elements of Luther is its love affair with the seedy side of contemporary London; where a crime thriller of half a century ago might have pored over the bright lights of Soho, urban terror in 2018 is a whistling bike wheel moving in the distance amid a landscape of deserted bus stops and desolate underpasses, or it's the harsh lighting on a supposedly empty night bus, a scenario which gives us one stand-out terrifying scene.

It's also a woman's late-night walk home through a deserted housing estate, where the creeping menace of one of a gang of noisy lads peeling off from the pack to shadow her is bait-and-switched before the audience into something altogether more terrifying. A serial killer is on the loose, one with a fearsome clown's mask and light-encircled duffel coat (to confuse CCTV) image and an interest in piquerism; sexual pleasure in piercing the skin.

At the same time, the son of gang boss George Cornelius (Patrick Malahide) has been abducted, and the cranky old guvnor finds himself on both sides of the hunter and hunted fence. Many viewers might have seen the preview clip in which Luther is abducted by Cornelius' men, tortured for information about the kidnapping, and breaks free in a burst of violently irascible swagger; it's the one time in this episode where Elba gets to truly cut loose from the police procedural motions and deliver on Luther's swaggering menace ('George, I don't care about you and I don't care about your son,' he growls, tables turned, 'all I care about is goin' home').

These are the best parts, the deftly-played scenes of crime horror and the leading talent making good on his promise. As DS Catherine Halliday, Wunmi Mosaku – previously seen in the BBC drama Damilola, Our Loved Boy – has just about enough screentime to get a foothold in Luther's world. 'Don't show her how it's done, show her how it's supposed to be done,' Superintendent Schenk (Dermot Crowley) tells Luther. 'Is this normal?' asks Halliday over a mutilated corpse in a playground. In Luther's world, she'd better get used to it.

Hermione Norris' haughty psychiatrist Vivien Lake is also a character with a lot of promise, although it feels like suspicion somehow falls upon her too easily, forcing the character down avenues she might have taken more steadily. Yet by the end of the episode, what looks like a neat done-in-one mystery has exploded into something more potentially sprawling – and from this intriguing, action-heavy start, we won't know how well the story truly plays itself out until the end of the week.

Luther series 5 premieres on BBC One on Tue 5 Jan at 9pm.