Another from last week's reading - opening salvo in the Holger Munch & Mia Kruger series.
From the Blurb:
A six year old girl is found hanging from a tree. Around her neck is an airline tag which says 'I'm travelling alone'.
A special homicide unit in Oslo is re-opened with veteran police investigator Holger Munch at the helm. He must convince his erstwhile partner, Mia Kruger, an extremely talented but eccentric investigator, to leave the solitary island to which she has retreated in order to take her own life.
When scrutinising the murder files, Mia spots the number One carved into the dead girl's fingernail. She returns to duty to prevent more little girls falling victim to a terrifying, revenge-driven serial killer...