Louise Penny’s All the Devils Are Here (2020) is the 16th novel in the Inspector Gamache series, and the first to be set outside of Canada. It is a contemporary mystery-thriller that explores the power of corporations on the modern world and the influences of troubled history on modern life in the diverse and complex city of Paris.

Plot Summary

Armand Gamache, head of homicide investigation at the Sûrete de Québec, travels to Paris with his wife Reine-Marie. Both his adult children have recently moved there. His daughter Annie, married to his former second-in-command Jean-Guy Beauvoir, is pregnant with their second child. Jean-Guy has recently left the demanding and dangerous job of the Sûrete for a consulting position at GHS Engineering, a private engineering firm. Armand’s son Daniel and his wife Roslyn have also moved to Paris with their two daughters for Daniel’s new job at an important Parisian bank.

The Gamaches go to Paris in preparation for Annie’s second childbirth, and Armand makes sure to spend time with Stephen, a close family friend and billionaire who is now 93 years old. After a family dinner out, Stephen is struck by a delivery truck and falls into a coma . The Gamache family is sure that it was not an accident. The Prefect of Paris Police, Claude Dussault, takes over the case. Claude has a new second-in-command, a formidable woman named Irene Fontaine.

Armand and Reine-Marie enter Stephen’s apartment and find a dead body among the rampaged apartment. He sends Reine-Marie outside while he tries to track down the intruder, but they get away. The murdered man in Stephen’s apartment is Alexander Francis Plessner, an engineer and investor in engineering patents. Armand has never heard of Plessner before. He discovers that Plessner and Stephen have been staying in a luxury suite at the Hotel George V instead of in Stephen’s apartment.

Armand begins suspecting Claude Dussault of covering up a complex crime. He and Jean-Guy discover that SecurForte, an elite security organization, is owned by the same partner companies that own GHS Engineering. They uncover evidence that Stephen had been involved in some way with GHS Engineering, and they race to uncover what the connections are between SecurForte, GHs Engineering, and the attempt on Stephen’s life.

Soon, Jean-Guy and Armand figure out that they’re being followed by SecurForte and a man named Xavier Loiselle. Jean-Guy also finds Séverine Arbour, a colleague who seems to dislike him but also appears to know much about the Luxembourg and Patagonia projects, the GHS Engineering projects that Stephen had been looking into. Armand is sure that Claude Dussault is involved because his previous second-in-command, Thierry Girard, is now the head of SecurForte. Armand also discovers that recently Stephen had been getting rid of his entire fortune. It seems that Stephen and Alex Plessner had been investing in GHS’s partner companies as a way of getting closer to GHS’s Board of Directors.

With the cooperation of Séverine Arbour, Armand learns about neodymium, a rare earth element used in magnets and technology. Daniel is captured by SecurForte, and Claude meets with Armand to bring him to Daniel. Claude, Loiselle, and Girard tell Armand that they are looking for the evidence Stephen found about GHS Engineering. They give Armand the night to find the evidence, or they will kill Daniel.

Racing to save his son, Armand meets Alain Pinot, the owner of the media conglomerate Agence France Presse and a board member of GHS Engineering. He was also a friend of Stephen Horowitz. Alain agrees to help Armand. Armand discovers that a reporter had been investigating a trail derailment in Colombia. This led her to the GHS mine in Patagonia, where she ended up dead—killed by GHS for asking too many questions. Armand figures out that neodymium is explosive when exposed to extreme weathers and was responsible for the train derailment. GHS also has recently built nuclear power plants using neodymium. Armand finds evidence of GHS’s wrongdoings before he is chased away by Loiselle’s gunfire. All of this occurs as Annie goes into labor.

Armand races to Stephen’s apartment, where Daniel is being held, and a shoot-out occurs. Believing that both Armand and Claude are dead, Girard takes the file of evidence and accompanies Alain Pinot to the GHS board meeting. It turns out Alain has been involved the entire time in covering up GHS news and murders.

However, Armand and Claude are actually unharmed—and allies. Armand explains how he finally figured out that he and Claude are on the same side. Armand goes to the hospital to meet his new granddaughter, and Claude and Daniel head to the board meeting. To make sure he can arrest CEO Madame Roquebrune, Girard must hand the file of evidence over to her and she must accept it. When they arrive at the meeting, Daniel informs Alain that because Stephen is in critical condition, Armand Gamache is executor of his business for the time being. If Armand puts Daniel on the board, then Alain must go. Claude explains the entire litany of crimes and misdeeds to the board of wealthy and international figures. He arrests Girard and Roquebrune.

Stephen miraculously survives through his coma. By the end of the novel, Stephen moves to Québec with Reine-Marie and Armand, as do Armand’s children and their families. Daniel and Armand’s relationship is healed, and GHS Engineering is dismantled.