Herbert Molin, a retired police officer, is living alone in a remote cottage in the vast forests of northern Sweden. He has two obsessions: one is the tango & the other is a conviction that he is being hunted, constantly pursued by 'demons'. He has no close friends, no close neighbours, & by the time his body is eventually found, Molin is almost unrecognisable. Lindman, a police officer on extended sick leave, hears of the death of his former colleague &, to take his mind off his own problems, decides to involve himself in the case. What he discovers, to his horror & disbelief, is a network of evil almost unimaginable in this remote district, & one which seems impossible to link to Molin's death.