Stonemouth

9pm, BBC One

There's no mention of exploding grandmothers, but most fans of the late Iain Banks welcomed his 2012 novel Stonemouth as a partial return to territory explored in one of the author's most celebrated books, 1992's The Crow Road: another young man adrift in another fictional but felt Scottish small town, caught in another tangle of family secrets and unrequited love while nosing into another unsolved mystery, and learning more about himself on the way.

Stewart Gilmour (played in the BBC's two-part adaptation by Christian Cook), is a 20-something making a tentative reappearance in the Aberdeenshire estuary town he grew up in, after having been chased out five years earlier by the Murstons, one of two criminal families who have what there is of the fishy little place carved up between them. Just why they ran Stewart out on a rail is revealed soon enough - suffice it to say it involved him and Ellie (Charlotte Spencer), eldest daughter of the Murston brood, and that the clan's thug patriarch, Don Murston (Peter Mullan), would be happy to see his head on a spike.

There is a more pressing mystery, however. Stewart's best friend, Cal Murston, Don's son, is dead. It seems he threw himself from the suspension bridge that looms high over the bay.

Stewart, who has been living in London, has been granted fragile dispensation from Don, and given temporary permission to come home for the funeral, so long as he doesn't hang around and - especially - doesn't contact Ellie. As for Cal, well, suicide is the story everyone has agreed on but, as he walks the old streets, Stewart is increasingly unconvinced. The stories he hears about Cal's depression don't tally with his memories of his friend. Then there is the question of the message Cal left on Stewart's phone shortly before he died, in which he spoke of having gotten himself into trouble...

Despite surface similarities between the two, Stonemouth is a more conventional narrative than The Crow Road, its pleasures more settled and subtle.

The basic plot - the outcast returning home, and seeing it with outsider's eyes - is a classic standard that was probably invented by the Greeks, and has certainly been reused in countless westerns and films noir.

It's the specific variations that matter: here, the sense of stubborn, decaying stasis Stewart recognises in the little town, while the world continues to move on beyond.

Chief among the strengths of Banks's book is the unfolding of Stewart's thinking and understanding, relayed direct from his mind to the reader's via the first-person narration. David Kane, the writer who has adapted the novel, stays true to Banks here, with Cook narrating Stewart's thoughts.

However, such faithfulness isn't always the most elegant solution. What works on the page doesn't always onscreen and, rather than putting us inside Stewart's mind, the voiceover here often gets in the way, propping scenes up, bluntly gluing them together and flattening the atmosphere.

Kane, on familiar ground following his work on the crime series Shetland, keeps the mystery moving, though, and he and director Charles Martin make excellent use of their Aberdeenshire setting. Mullan, unavoidably, perhaps correctly, dominates the cast (especially while doing his dance exercises) and there's great work from Brian Gleeson as his right-hand man.

But it's the Stonemouth in the background (played by the Banff Bay town of Macduff) that becomes the strongest character, leaving you with the sense it will still be there after everyone is gone, and all their secrets forgotten.