ARNALDUR INDRIDASON'S SHADOW KILLER

It is Rekyjavik, in the summer of 1941, after what one character calls 'the British invasion' of the island, and the Brits are in the process of handing over occupation of the strategic country to the Americans, who although still neutral, need to protect their convoys. When a traveling salesman is found shot dead in his flat, Iceland's only homicide detective, Flovent, is teamed up with a Canadian military policeman, Thorson, whose parents were Icelandic and who speaks the language. Thorson is necessary because the victim has been killed with a bullet from a Colt automatic, which means the killer very well could be an American soldier.

The Shadow Killer is the second in Indridason's 'Rekyjavik Wartime' series. It takes place before the first, The Shadow District, which began with a crime in the present day and flashed back to another murder which Flovent and Thorson investigated. This book shows how the two were brought together, and also shows the transition in Icelandic society, which was such an important theme in his Erlandur novels, also coming together with the influx of British and especially American soldiers. In such an homogenous, inward society, this impact, on social norms as well as economic life, was immense.

These changes have been part of most of the very best of Scandinavian crime fiction, going right back to Sjovall and Wahloo's Martin Beck: how these small, structured societies have adapted to the changing modern world. Indridason's first book, Jar City (aka Tainted Blood) was specifically linked to the unusual genetic 'purity' of Iceland, and with this series set some eight decades ago, he has a smaller, more distinct petri dish to play on his themes of Icelandic society under the pressure of change. And because it's wartime. it also allows him to revisit another recurring theme in Scandinavian crime: the ambivalent record of the Nordic countries during World War II, during which Noway and Denmark were occupied by the Nazis, Iceland by the Allies, Finland fought the Russians, and the Swedes stayed neutral. This legacy does not disappear: it played a part in one of the Rebecka Martinson films recently aired on British TV.

But the murder might be a simple case of jealousy, as the dead man's girlfriend was playing around with soldiers while he was away on his selling trips, and had just moved out with a British soldier while he was gone. Neat as such a theory would be, there are shadows hanging over the investigation, and German-supporting Icelanders popping up. With Thorson and Flovent having to move between both American intelligence and the British, as well as understand Icelandic mores, the mystery becomes more and more complicated, yet its solving may be more complicated than the mystery itself.

Indridason has produced a multi-layered thriller that delves delicately, almost discreetly, into its characters. He writes with tremendous feel for them, and uses action to let those character reveal themselves. It's a mistake for Brits to label the likes of Flovent or Thorson 'depressive detectives': they are people, and that realisation has always been what makes the best Scandianvian crime fiction work so well. That it is used in such a complicated historical setting marks yet again just how talented this Icelandic novelist is.

The Shadow Killer by Arnaldur Indridason
Harvill Secker, £14.99 ISBN 9781911215073