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 beloved Christmases have come at once - but filming is soon slowed down 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 are prepared 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.