With his sniffer dog, Pippin, Dr. Peter Bannerman uncovers suspects, treats animals, tracks a kitten kidnapper, and must solve a locked-room mystery.

In the fourth book in the series, Dr. Peter Bannerman's brother Sam takes in three Bengal kittens after the previous owner, his neighbor in a Winnipeg north end apartment building, is found dead. The death was originally thought to be due to accidental autoerotic asphyxiation, but after investigation, Sam is arrested and charged with his neighbor's murder.

Sam suffers from several mental health conditions, but Peter refuses to believe that he is capable of killing someone, so he sets out to prove his innocence. Sam, however, is more concerned about one of the kittens who has gone missing. With the help of his talented sniffer dog, Pippin, Peter tries to find the kitten, as well as evidence that someone else murdered the neighbor.

Peter talks to the other people in Sam's building, and several appear to be plausible alternative killers. However, by that time Sam, still in custody, begins to rave about ghosts being the real murderers and insists Peter investigate that. Despite not believing in ghosts (not in the slightest), he has a terrifying experience while spending the night in Sam's apartment.

The situation rapidly spirals, putting Peter and Pippin in peril and ultimately revealing a story of revenge served cold from decades ago and continents away.