It's 1941, and the Mitford clan gathers at Chatsworth for Christmas, along with a selection of society's most impressive and glamorous guests, plus old family friend Louisa Cannon, a private detective. During a séance, the psychic reveals that a maid was murdered in this very same house—and she can prove it. Louisa steps forward to try to solve the cold case, but with a house full of people who want nothing more than to bury their secrets, will she be able to unmask the murderer?