Saddlebag preacher Thaddeus Lewis loses his daughter under strange circumstances, and when another girl dies in the same way, he realizes that a murderer is loose in Upper Canada. Unrest following the 1837 Mackenzie Rebellion, however, occupies the authorities.

Over the next four years, Lewis discovers other similar murders. Suspicion falls on his own son-in-law, two artists, a failed preacher and a peddler. Lewis narrows the list until evidence points to the peddler Simms, tortured by an incestuous relationship with his sister. Twisted guilt has driven him to kill women who resemble her.

In the course of Simms' apprehension and eventual confession, Lewis is forced to re-examine his own attitudes and beliefs.

The story is loosely based on an anecdote from a privately published autobiography. The history of the Rebellion, the Patriot Hunter invasions, Pirate Bill Johnston and Upper Canadian politics are woven into this tale of serial murder.