Knave of Diamonds - Laurie R. Kingová

When Mary Russell was a child, she adored her Uncle Jake, the black sheep of the family. But she hasn't heard from him in many years, until he presents himself at her door with an abundance of problems for his clever niece to deal with. Not the least of which is the reason the family rejected him in the first place: his involvement in the infamous disappearance of the Irish Crown Jewels from Dublin Castle in 1907. It was a theft that shook a government, enraged a King and threatened the establishment. Juggling conflicting loyalties and international secrets, Russell is entangled in the web of a case that not even the great Sherlock Holmes could solve.