It's Christmas 1936 and an eclectic list of guests and staff have gathered for the grand re-opening of Maybridge castle, a newly renovated yet still crumbling hotel deep in the Cumbrian countryside. They are:

The ex-socialite owner
The Doctor and his new wife
The stylish journalist
The know-all housekeepers
The still-grieving widower and his son
The tarot readers
The passionate academic
The persistent investigative reporter
The elder amateur sleuth, and her cat

An innocent game of murder-in-the-dark will turn into a real game of life and death. And by the time the first sherries have been drunk, one of these people will be dead - and one of them the killer. Someone has changed the rules, but who?