Christmas has come to Marquess House and with it, an unexpected mystery for Perdita and Piper to solve.

Will they be able to reunite sisters whose story has been lost to the past?

The Convent of Llyn Cel Island, 1486

Mother Superior, Sister Non, returns from a family wedding to discover the bones of a saint have been revealed during a storm. As her ecclesiastical superiors make plans for a Holy Shrine to be erected, Sister Non knows she must stop them before her bitter secret is revealed.

Present Day, Marquess House, Pembrokeshire

Perdita and Piper Rivers are spending their first Christmas at Marquess House but when lightning strikes the ancient tower at the heart of their manor revealing a hidden reliquary they are unexpectedly drawn into a ghost story. With Kit Mackensie and Callum Black, Perdita and Piper delve deep into the past to help a centuries old story finally reaches its conclusion.