December in Glendara, Inishowen, and solicitor Benedicta 'Ben' O'Keeffe is working flat-out before the holidays; the one bright spot on her horizon is spending her first Christmas with Sergeant Tom Molloy.

But on a trip to Dublin to visit her parents, she bumps into Luke Kirby - the man who killed her sister - freshly released from jail. He apologises to her; remorseful, conciliatory ... but as she walks away, he whispers something that chills her to the bone.

Back in Glendara, there is chaos. The Oak pub has burned down and Carole Kearney, the Oak's barmaid, has gone missing. And then on Christmas morning, while walking up Sliabh Sneacht, Ben and Molloy make a gruesome discovery: a body lying face-down in the snow ... Soon it becomes clear that these events are part of a plan for revenge that will have devastating consequences for Glendara's residents.