Death in Dalvik (Fire and Ice #6 - 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 Dalvik 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.