RAGNAR JONASSON'S THE DARKNESS

Hulda Hermannsdottir is approaching her retirement from the Reykjavik police. She's just cracked a hit and run, where the victim was a child-molester, and she has decided to leave the case unsolved. At the same time, she is called into her boss' office, and told to take her retirement early, immediately, in fact, and to clear her office for another in a long series of up-and-coming younger men who passed her by during her long career.

As slight recompense, Hulda gets her boss' agreement to work one last case, and chooses the death of a Russian asylum-seeker which had been written off a year earlier as suicide or accident by one of her colleagues. It doesn't take Hulda, who is a methodical, dedicated worker, to uncover evidence that the death may have been a murder.

At first, the impressive thing about The Darkness is the way Hulda fits into that popular stereotype of the depressive Nordic detective. Hard-working, team-playing and alone since the death of her husband to a sudden heart attack aged 52, Hulda has little in the way of a life outside her job: she walks and climbs in the countryside, but gave up the family home by the shore and now lives in a faceless high-rise in Reykjavik itself.

But as the story progresses, and we begin to see more of the original crime, we also learn more about Hulda's own story: born illegitimate, her father a nameless American solider who disappeared back to States, her mother forced to live in a certain shame by the tight boundaries of Icelandic society. If we thought of Hulda as typical of a certain kind of detective, we see too that she is a product of a society which in many ways has changed, but whose emotional bounds were set pretty strongly generations before. And now she is one of those older Icelanders who discover they are easily pushed aside, easily disappeared.

In fact, Jonasson's two stories move almost in parallel, the the mystery of Hulda herself is in many ways as gripping as the search for a killer in a murder no one but Hulda believes happened. Jonasson tells the killer's story from a separate point of view, and because of this, the sharp-eyed reader will know long before Hulda who the killer must be. Even so, the 'solution' to the crime comes as a sharp twist in the tale, one which plays against the reader's expectations. Were the story left there, it would resonate strongly. But in an epilogue of understated brilliance, Jonasson turns the entire story around on itself, and puts Hulda right back where she started, a victim, of sorts, of society's preconceptions.

Jonasson, whose first novels were more traditional mysteries set in small-town Iceland, a setting which became well-known in similarly-set popular series Trapped, has moved into different territory with The Darkness. The book is billed as the first of a 'Hidden Iceland' trilogy, and the hidden Iceland it traverses is the country of the mind. The Darkness builds to an absolutely moving ending, haunting and sobering. And it plays with and shatters the expectations of the genre like no novel I can recall since Joe Gores' classic Interface, which is high praise indeed. It's a bravura piece of writing, and The Darkness may be the most unsettling, lasting and best, crime novel you'll read this year.

The Darkness by Ragnar Jonasson
Penguin: Michael Joseph, £12.99, ISBN 9780718187248