Maureen Beattie as Chief Superindent Isobel McArthur 3

Why do we see so many cop shows on TV and so few on the stage? That’s precisely the question that Edinburgh’s renowned crime writer Ian Rankin poses in the programme to his new show Dark Road at the Lyceum Theatre, co-written with the theatre’s artistic director Mark Thomson.

It’s not an easy question to answer. Maybe it’s simply because the genre is so prevalent on TV and in novels. Or maybe it’s because we expect something different (or even something more?) in the theatre. Rankin and Thomson’s achievement – sometimes sordid and shocking, sometimes thoughtful and probing – isn’t without its problems. But its provocative themes and sheer theatrical exuberance (aided strongly by Francis O’Connor’s elegantly revolving set) nevertheless make a strong case for crime as a striking and unpretentious stage genre.

Isobel McArthur is Scotland’s first female chief superintendent, and after 30 years’ service she’s considering writing a memoir of her time on the force – neatly coinciding with the 25th anniversary of her sending down Alfred Chalmers, a grisly Edinburgh serial killer of teenage girls. Nagged by doubts about the case, McArthur begins a dangerous journey in a search for fresh answers, taking her family and colleagues with her on a path that quickly plummets into darkness.

As so often in his novels, Rankin’s characters in the play are balanced precariously between black and white – none more so than McArthur, in a superb performance from Maureen Beattie that convincingly combines vulnerability with a sure sense of her own power. It could be her instinct for justice that pushes McArthur to reopen the case – or it could simply be a desire for fame and money as she hits the highpoint of her career. It’s the volatile Chalmers (an appropriately slippery Philip Whitchurch) who will sell her book, after all.

Likewise, her teenage daughter Alexandra – a feisty yet needy Sara Vickers – invites our judgement with the activities (rather overstated) in her personal life, yet longs for a more fulfilling relationship with her mother. Vickers knows well how to arouse our sympathy – yet Alexandra’s surprising discovery of an unlikely father figure pushes credibility a bit too far.

Its explorations of family and loyalty are one theme that takes Rankin and Thomson’s play to a different level from TV cop dramas, and the writers nicely contrast the functional, albeit temperamental, ‘family’ that McArthur has had at work – with Robert Gwilym all simmering energy as colleague and ex-lover Frank, and Ron Donachie quietly authoritative (but frustratingly underwritten) as ex-boss Fergus – with the well-meaning mess of her domestic life.

There are several threads that don’t connect, more than a few unlikely coincidences, and a couple of grotesque dream sequences that threaten to shatter the grubby naturalism found elsewhere. Police interview tapes are too readily used for exposition, slamming the breaks on the action and often simply proving hard to hear. The second half has enough twists and turns to risk fracturing the plot entirely.

But when Rankin and Thomson finally show their hand in the play’s genuinely chilling conclusion, it seems to come from nowhere and yet was predictable all along. Its admittedly compelling brutality might verge on melodrama, but it serves to reiterate the play’s themes of familial loyalty to breathtaking – and shattering – effect.

Dark Road continues at the Lyceum Theatre until 19 October

Robert Gwilym as Frank Bowman , Ron Donachie as Fergus McLintock and Maureen Beattie as Isobel McArthur