In the 1760s in a remote area of France, a number of people (probably a hundred or so) were killed or wounded in animal attacks. Victims and witnesses alleged various odd things about the attacker, claiming it was different from a wolf or other animals they were familiar with in that it had strange coloring, or was bigger, or was bipedal, or could leap supernaturally high, or had a strong peculiar odor, etc. As the stories got told and exaggerated, there arose various theories that a werewolf, a devil, an animal imported from Africa, or some other kind of monster was responsible for the killings.
Monsters of the Gévaudan is a meticulously researched inquiry into this legend, written in a dry, academic style. It’s not presented in a popular way, and it’s not presented as a mystery about what the beast really was. (The author states in the introduction that the victims of the “beast” were almost certainly just killed by ordinary wolves, something not at all unusual in that area.) Indeed, he downplays the very question of what the beast was, as he’s more interested in exploring all the social and political things going on at the time that are relevant to how the myth got started and spread and such.
So basically it’s a dry social history of France in the 1760s that uses this myth as something to organize around.
There were many elements that came together to create the legend of the beast. The Gévaudan was a miserably poor, sparsely populated, poorly educated, rural area. The King and the military wanted a big victory for public relations purposes, since they had just gotten their butt kicked in the Seven Years War, so the hunters they sent had to be depicted as coming to save the day by battling a worthy adversary. In intellectual circles, there was considerable interest in exotic animal species, hybrids, possible monsters, etc.
As important as anything in making the story a big deal was the rise of sensationalist periodicals. They no longer had a war to report on, but they still wanted a big story, and a monster raging through the countryside fit the bill. The periodicals were not above making up details to make the story more appealing to readers.
As each group of hunters sent to kill the beast failed, they had an incentive to exaggerate its prowess, to explain why they had failed and why they were entitled to more time and resources.
The local people often responded to the hunters and other outsiders as a bunch of arrogant, incompetent asses.
Eventually, when the story ran its course and the powers that be were actually losing face rather than benefitting the longer it dragged on, they pretty much decided just to declare an above average size wolf that had been killed the beast. The hunter who had killed it was lauded for his great accomplishment, and victory was declared. When the animal was stuffed and brought to the capital, people had to go through the charade of pretending it was something more than an obvious wolf.
Overall, Monsters of the Gévaudan seems to be very well done for what it is, but for the overwhelming majority of readers I suspect it’s not something they would enjoy as entertainment. It’s an academic work that meticulously and exhaustively describes a little historical niche. So it adds to overall human knowledge in a way academia is supposed to, and in that sense is a success, but it’s not something I would recommend for general readers.