The Nature of the Beast is a mystery novel by Canadian novelist Louise Penny. Published in 2015, it is the 11th novel in the Chief Inspector Gamache series. Like all novels in this series, the plot revolves around a crime connected to the isolated village of Three Pines and the local community and explores the destructive effects of lies, secrecy, and moral ambiguity amongst the hidden tensions of a small-town setting.

Penny has lived in a small community in the Eastern Townships region of the province of Quebec, Canada, for many years, and has therefore modelled the fictional town of Three Pines on her memories and experiences in this region.

This guide refers to the Minotaur Books 2015 hardcover edition.

Content Warning: Both the novel and this guide contain references to the violent death of a child and to war crimes.

Plot Summary

At the start of the novel, Armand Gamache has recently retired from his role as the Head of the Sureté du Quebec (the province-wide police force) and has moved to the isolated and close-knit village of Three Pines, Quebec. Many members of the community have taken on roles in an amateur theatre project led by Antoinette Lemaitre and her partner, Brian Fitzgerald. The group is preparing to perform a play entitled She Sat Down and Wept; Antoinette found the script in some papers she inherited from her late uncle, Guillaume Couture, and is very impressed by it. However, the author of the play is revealed to be John Fleming, a notorious serial killer who has been imprisoned for decades, and Gamache is particularly insistent the play should not be performed. He knows details about Fleming’s crimes that were never released to the public and believes that Fleming is the embodiment of pure evil.

Debates about the play are interrupted when a nine-year-old boy named Laurent Lepage tells a gathering of villagers, including Gamache, that he has found a giant gun in the woods near the town. No one believes Laurent because he has a history of inventing wild stories. However, Laurent’s body is found the next day, and Gamache believes the death to be suspicious. While looking for clues to determine whether Laurent’s death was a murder or an accident, Gamache searches the woods and finds a giant supergun that is capable of launching missiles or other weapons of mass destruction. It is now clear that Laurent was telling the truth and that someone likely killed the boy to keep the existence of the gun a secret.

Gamache’s son-in-law, Jean-Guy Beauvoir, is a high-ranking police agent; he and other police colleagues investigate the murder of Laurent and the presence of the supergun, and Gamache contributes informally to the investigation. A retired physics professor named Michael Rosenblatt is brought in to consult on the case, along with Mary Fraser and Sean Delorme, two agents from CSIS (the Canadian intelligence agency). Through research and information gathered from these experts, Gamache learns about the history of the supergun. In the 1980s, there were many rumors that a brilliant Canadian engineer named Gerald Bull was secretly working on designing a giant supergun and would be willing to sell this weapon to whoever would buy it, thus creating a significant security threat. Bull was murdered in 1990, and most people eventually assumed that the supergun project, nicknamed Project Babylon, was simply a rumor.

However, because the giant gun is etched with an illustration of an image known as the Beast of Babylon, the discovery confirms that Bull succeeded in creating this weapon. The supergun is missing the firing mechanism and therefore poses no immediate threat, but if either the firing mechanism or the design plans fall into the wrong hands, it would constitute a threat to international security. While Gamache and his colleagues work quickly to learn more about the gun and to discover Laurent’s murderer, Antoinette Lemaitre is suddenly killed as well. Gamache realizes that Antoinette’s late uncle, Guillaume Couture, was once a collaborator with Gerald Bull; Couture was the one who actually designed the weapon. Gamache deduces that Antoinette’s murderer may have also killed Laurent and is now actively working to gain access to the firing mechanism, the design plans, or both.

Eventually, Gamache locates the firing mechanism for the gun; he also learns that there was a third collaborator working alongside Bull and Couture: the notorious serial killer, John Fleming. Before Fleming committed his murders, he worked on the supergun project, and he knows the location of the plans. As Fleming taunts Gamache with this knowledge, the situation is growing more desperate because word of the supergun has been leaked to news sources and a variety of criminals and arms dealers will soon be racing to locate and claim the plans for themselves. Out of sheer desperation, Gamache even considers taking Fleming out of prison to get information about the location of the plans, but at the last minute, he uses certain clues hidden in the manuscript of Fleming’s play to locate the plans himself.

In an attempt to seize the plans, the CSIS agents confront Gamache, but Jean-Guy destroys the plans. The connection of the CSIS agents and Professor Rosenblatt to Project Babylon is never clarified, and their motivations remain uncertain. It is revealed that Brian Fitzgerald was the one who killed Laurent and Antoinette because he became obsessed with the possibility of a supergun and Guillaume Couture’s connection to it before he ever met Antoinette. In fact, he only pursued a relationship with her so that he could search for plans related to the gun. When he heard Laurent’s claims about the gun, Brian killed the young boy to prevent others from finding it, and he later killed Antoinette when she interrupted his search for the plans. Brian is arrested for these crimes, and peace is restored to Three Pines.