Captain Hal Stirling is flown to England from Afghanistan after a roadside bomb renders him battered and broken.

Once home, he retreats to his ancestral family seat of Stirling Towers -- a gothic mansion that dominates the landscape near the remote Scottish Borders -- for a Christmas of quiet recuperation. But on arrival he discovers that his mother, a fanatical spiritualist, has died and been hastily buried.

Isolated from the insular local community, Hal finds himself at the mercy of his mother's two mysterious nurses, the harshest winter on record and, before long, the horrific visions; experiences he attributes to his heavy medication. Yet as the December weather deteriorates, so does Hal's certainty that his home is a place of safety.

Who, or what, is trying to frighten him to death?