David Rousseau, writer of detective novels lacking inspiration, returns to Mouthe, a village in the Jura where he spent part of his childhood, reputed to be the coldest in France. A monk, Brother Giacomo, promised to tell him a secret about his mother. On his arrival, David learns that the monk in question is dead, while strange events disrupt the frozen daily life of the village: the discovery of a human ear, then that of a corpse imitating a self-portrait of Van Gogh. To the despair of the local gendarme, Warrant Officer Louvetot, David interferes in the investigation by constructing hypotheses worthy of his novels. Could a serial killer be hiding... in Mouthe?