Avalon Castle is an unusual, disturbing place. Painstakingly built by Ambrose Blackwood, an eccentric obsessed by the legends of King Arthur, and inhabited by the rest of the dysfunctional Blackwood family, Avalon Castle houses some very dark secrets. When Rachel Garland visits, she hopes to spend the Christmas of 1867 peacefully with her half-sister Lucy who is living there. What she finds is a house filled with family feuding, rumoured hauntings and unnerving disappearances. Any chance of festivity is halted by the sudden death of a house member. Rachel's discomfort grows as her questions mount: who is this strange family, and what skeletons are being hidden within their vast house? With the help of William Norton, a neighbouring land-owner who makes Rachel's acquaintance, she searches for evidence to prove her suspicions of foul-play, but her quest leads her into deadly peril.