Christmas is coming and the snow is falling, but with the de Luce family finances in a parlous state, Colonel de Luce has been forced to rent out the family home to a film company. For Flavia and her sisters it's as if all their belated Christmases have come at once - but filming is soon slowed by a series of nasty accidents and then brought to a halt as a heavy snowstorm cuts Buckshaw off from the outside world.

As they prepare to wait out the weather, they are stunned by a gruesomely dramatic murder - and suddenly Flavia, in the midst of designing an experiment to prove the existence of Father Christmas - has another, far deadlier mystery to solve.