It is December 1922, and the keepers of the Kinvara Light, an impressive lighthouse just off the rugged west coast of Scotland, are home for Christmas after three bleak months away from their families. Robert Sutherland, deputy head keeper, finds little comfort at home: his wife Hannah is embittered by her isolation, by the tragedy of her infant son's cerebral palsy and by her husband's long absences. Rob find solace in the arms of Morna Jean Sommero, whose warmth and love compensate for his sterile marriage. Their affair is just one of the secrets of Kinvara, whose dramatic and colourful characters live out their lives against an unforgiving landscape.