Twelve years ago, eight friends ran an exclusive group at university: The Murder Masquerade Society. The mysteries they solved may have been grisly, but they were always fictional - until their final Christmas Masquerade, when one of the group disappeared, never to be seen again. Now, the remaining members of the group receive an invitation to a reunion masquerade, to be held in a beautiful and remote country house in Scotland. When they arrive they are each assigned a new identity themed around the Twelve Days of Christmas - they become Lady Partridge or Mr Gold; Lord Leapworth or Doctor Swan. The game begins, and it feels just like old times. Until the next morning, when Lady Partridge is found hanging from a pear tree.