Hestan Island, marooned in the Solway Firth, tethered to the mainland at low tide by a causeway called The Rack; Hestan home to two men quietly living out their lives, until a boy is almost crushed to death in their tiny copper mine, when their shared past begins to unravel. Over at Balcary House, Brogar Finn and Sholto McKay arrive, and soon become involved in the affairs on Hestan, which in turn leads them back through the bloody wars of Crimea and the lands of the Tartars.

The third in the Scottish Mysteries, Hidden Pasts is host to a complex plot that explores the history of a little known part of Scotland, and explores how small, seemingly insignificant, events can echo down the years, with deadly consequence.