Book excerpt: In this new extraordinary thriller from Gold Dagger Award winner Arnaldur Indridason, the Reykjavik police are called on an icy January day to a garden where a body has been found: a young, dark-skinned boy is frozen to the ground in a pool of his own blood. Erlendur and his team embark on their investigation and soon unearth tensions simmering beneath the surface of Iceland's outwardly liberal, multicultural society. Meanwhile, the boy's murder forces Erlendur to confront the tragedy in his own past. Soon, facts are emerging from the snow-filled darkness that are more chilling even than the Arctic night.