The book begins with Slim sneaking up on, and killing, a "goblin or beast" on the fair grounds of a local carnival. Goblins are monsters which can shape shift between human and bestial forms, genetically engineered super-predators which desire bloodshed and human misery. Created in an ancient, technologically superior era of human civilization, they exist to torment and ultimately murder humans. They can only be seen by a few people, including Slim himself, Rya Raines (his wife), and Joel Tuck (Slim's friend and fellow carnie). These goblins are superhuman and extremely dangerous and genocidal, at least as intelligent as us, and can mimic human behavior. While they appear and act as a normal person would, they experience only negative emotions like fear and hate. Their only pleasure is in torturing and murdering humans.
After this encounter, Slim proceeds to join the carnival (one of many he has drifted from) as a way to support himself while killing goblins and hiding from his murderous past (in which he killed an uncle by marriage that was a goblin responsible for the deaths of several family members). One of the prominent members of the "carnies" is a young woman named Rya Raines, who quickly becomes his lover and confidant. As their relationship matures, Slim has several more run-ins with the goblins which leads to the revelation that his friend Joel, and even Rya herself, can see the goblins too, and that each of them in their own way has suffered terribly from the goblins' actions in their past. It is soon revealed that Rya had long before made a pact with the goblins to report to them whenever she found someone who could see through their disguise in exchange for safety from their predations. She wants him to make the same pact with them, but he refuses. This reality creates a gulf between her and Slim that comes to bloodshed between them. She regrets this later and after reconciling with Slim she becomes his wife. They decide to go on a mission to destroy any and all of the creatures they possibly can.
Inside the Live Reptile Tent takes us on a journey to the heart of American recreation, traveling through the carnival midway. with its amusement rides, brightly colored booths, and beseeching barkers. Included are photographs of freak shows, fast-food booths, vertiginous rides and rigged games, all captured in the melancholy light of past glories and eroding imaginations. Jeff Brouws's images of nostalgia hold a prominent place in the American consciousness.
A lonely, contemplative wanderer reaching at twilight a city where a carnival is in full sway. On every side is heard the clangor of instruments mingled with shouts of joy and unrestrained hilarity of the people giving vent to their feelings in songs and dance tunes. (From The Woodlands Symphony Orchestra)