While attending an agricultural show, Detective Murdoch is amazed at the quality and detail of a miniature street scene that is on display. It includes several houses and several miniature residents. It also includes a man standing in a second floor room pointing a rifle. Murdoch quickly concludes that he is looking at the recreation of a murder scene. He quickly finds the Toronto neighborhood depicted in the model and learns that it was created by Lydia Howland, an idiot-savant who does not speak but has a photographic memory. He is certain that she witnessed a murder and now has to figure how to get at her memories and determine which of the people depicted in the miniature is the real-life killer.