Detective Murdoch investigates the murder of Rod Grimsby, who was forced to drink varnish. What they also find at the crime scene is the man's son Harcourt Grimsby, a ventriloquist who does most of his talking through his puppet, Mycroft. The dead man was having an affair with his neighbor's wife so they have an obvious suspect, but Murdoch thinks the solution is far more complex. He is joined in his investigation by Arthur Conan Doyle, the creator of Sherlock Holmes, who has returned to Toronto with the intent of writing a new novel based on Murdoch's techniques. He also has another, far more personal reason for returning.