Britain 1941. Still reeling from the greatest loss of his life, the Reverend Major Clement Wisdom is called on again to serve his nation in its time of need. Under the cover of taking up a new parish in far northern Scotland, Clement is sent to the remote village of Huna, in Caithness, to locate a possible enemy agent who is sending out encrypted radio messages. Arriving in the depths of winter, Clement quickly finds it isn't only the temperature that is unnervingly cold. Perched on the edge of Great Britain, the isolated community is wary of strangers. Struggling to gain trust from the locals and where even his assigned government contact, the local postmistress is antagonistic, he becomes entangled in a web of silence. When the husband of his contact is found dead, the body horrifically impaled on a shard of window glass, Clement is at first unsure if it is an unfortunate accident, or a gruesome warning. As more deaths are uncovered, Clement realises he is facing not only an enemy spy but a ruthless killer. With limited time, Clement must act quickly, and if necessary, alone.