Death in Dalvik — Michael Ridpath

When sixteen-year-old Dísa is given five bitcoin by her divorced father she is unimpressed: she hasn't heard of the cryptocurrency, and five of anything can't be worth very much. But a year later, when her grandparents are about to lose the farm near the Icelandic village of Dalvík in the north of Iceland, where their family has lived for centuries, quiet, unassuming Dísa is able to rescue it with the profits from her astute trading of her father's gift.Unknown to Dísa, her mother Helga catches the cryptocurrency bug. Not only does Helga invest in Thomocoin, a new cryptocurrency sweeping Iceland, but she persuades many of her neighbours in Dalvík to invest too, taking a cut for herself.Helga is found murdered on the hillside above the farm and Inspector Magnus Jonson investigates. Magnus realizes that Dísa, now a nineteen-year-old student, can help him unveil the shadowy forces behind Thomocoin. But torn between loyalty to her family and fear for her life, Dísa has other ideas.