On an icy January day the Reykjavik police are called to a block of flats where a body has been found in the garden: a young, dark-skinned boy, frozen to the ground in a pool of his own blood. The discovery of a stab wound in his stomach extinguishes any hope that this was a tragic accident. Erlendur and his team embark on their investigation with little to go on but the news that the boy's Thai half-brother is missing. Is he implicated, or simply afraid for his own life? The investigation soon unearths tensions simmering beneath the surface of Iceland's outwardly liberal, multicultural society. A teacher at the boy's school makes no secret of his anti-immigration stance; incidents are reported between Icelandic pupils and the disaffected children of incomers; and, to confuse matters further, a suspected paedophile has been spotted in the area. 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.