Christmas is a special time of year for Psychic Nan Killian and Medium Sarah Lyon-White. It is special for their friends, Doctor John Watson, and his wife Mary. It is also special to others... for very different reasons. For Christmas Eve is also hallowed to dark forces. When women keep going missing and then turning up insane, it's up to Nan, Sarah and the Watsons to stop the darkness before it can conquer all.