Slàinte! A Christmas Eve party at snow-covered Vik castle, where the Christmas Star diamond is on display. Good food, dancing and a visit from Santa. What could possibly go wrong?

When Santa appears down the chimney, looking far more crispy than expected, it is clear that something has gone very wrong. With the castle cut off from help, a murderer in their midst and the Christmas Star stolen, it's up to Losers Club to investigate. As they follow the network of secret passages to learn more about their fellow guests, they realise that everyone has a motive. Including one of their own.