'Endgame has kept our secrets for half a century, now it's time for it, and its secrets, to have a new owner.' When Lily returns home to her aunt's manor house, she discovers that in order to inherit, she and her estranged cousins must stay together over the Christmas week and take part in a family tradition: the annual treasure hunt. But as they are drawn deeper into the game, the clues seem to point not to the deeds to the manor house, but to the key to a twenty-year-old mystery: what really happened to Lily's mother? As a snowstorm cuts them off from the village, it becomes apparent that the game has turned deadly and that Lily is fighting for more than just an inheritance: she is now fighting for her life. Does she have what it takes to survive? 12 clues, 12 keys and 12 days of Christmas for the heirs of Endgame House to find their inheritance, but how many will die before Twelfth Night?