Scandi-noir queen Karin Fossum brings familiar Inspector Konrad Sejer to an interview room in “The Whisperer.” There he spends much of the novel probing a dormouse of a woman who has clearly done something bad. Fossum delicately interleaves the charged discussions between cop and prisoner with the recent days of the woman, who had begun receiving threats. The interrogations are nuanced, the daily histories increasingly pregnant with violence. I enjoyed the cat-and-mouse very much, and the author’s masterful withholding of information works a treat, but there is only one problem. The final denouement reveals a tired plot that limps to a boring end. A pity that the technically adept construction is in aid of so little.