Will and Jim head out to check out the carnival, and to their surprise, it seems normal. They bump into Miss Foley, their seventh grade teacher, who is searching for her nephew Robert and heads off to the Mirror Maze, even though Will warns her not to. She goes in and panics, feeling lost. The boys manage to pull her out and she tells them that they must go find the little girl who is lost in there. Miss Foley goes home, and the boys stay away from the Mirror Maze.
At sunset Jim disappears, and Will goes into the Mirror Maze where he find his friend, transfixed. He pulls Jim out, who seems incoherent, muttering about how amazing it was. They start home, and Jim insists that they must return later that night. Will does not want to, but Jim says he knows that he can count on his friend. As they leave, they trip over a leather bag.
The boys realize that the bag belongs to the lightning-rod salesman, and they wonder why it is abandoned. Jim convinces Will that they must stay at the carnival to solve this mystery, and they stay while everyone else heads home to dinner.
Will and Jim look at a merry-go-round that, according to a sign, is out of order. Jim is not so sure, especially since it is the only ride they have not observed. Jim jumps on one of the horses, and the boys are startled to hear a voice telling him to leave. A man snatches Jim in his hand and grabs Will as well when he tries to help his friend. Another man tells the first to put the boys down. They look up and see a tall man in a suit. The suit is amazing to Will, because it looks like it is made of bristles, hair, and other itchy, uncomfortable substances, but it does not seem to bother the man, who looks only at Jim. He introduces himself as Mr. Dark, and tells them the red-haired man who picked them up is Mr. Cooger. Mr. Dark pulls back his sleeves and they see that he is the Illustrated Man, covered in tattoos. He asks Jim what his name is, and Jim tells him "Simon." Both smile because they know that Jim is lying. He shows Jim more of his tattoos and then tells the boys to leave and come back the next day.
They run off, but Jim looks back once and then jumps in a tree, telling Will to follow. The boys watch as Mr. Dark looks around and then starts up the merry-go- round. It runs backwards, as does the music, and Mr. Cooger jumps on. They see, to their disbelief, that Mr. Cooger is growing younger as the carousel spins around. When he gets off he is twelve years old, and he runs away across the field. Will and Jim slowly get down from their hiding place and then chase after the boy.
Will has a bad feeling about the carnival and it seems that he is correct. But Jim cannot help himself. He knows that the Mirror Maze was bad for Miss Foley but he has to see it for himself. What he sees changes his opinion, and he is angry with Will for pulling him out. Danger will not stop Jim from exploring something; in fact, it might make him more willing. His curiosity is endless and any adventure is fair game. But this attitude may get him into trouble, and Will is worried about his friend, especially when Jim insists on coming back at night. Then the boys find the lightning-rod salesman's bag, and things begin to take a more sinister turn.
Jim insists on exploring the merry-go-round, since it is the only ride that they have not looked at. Mr. Cooger, however, is there and seizes the boys. After Mr. Cooger puts the boys down, Mr. Dark begins to develop an interest in Jim. Jim is intrigued by Mr. Dark's tattoos. The fact that Mr. Dark entertains Jim and never once looks at Will implies some sort of sinister plan that Mr. Dark has for Jim. And it also becomes clear that Jim may be a willing part of whatever that plan is, because he is thrilled by his interaction with Mr. Dark. When Jim tells Mr. Dark that his name is "Simon" and then both smile, acknowledging the lie, it is clear that they are alike in some crucial ways. Mr. Dark seems to be a man of action, just as Jim is a child of action. The question that remains is what kind of action Mr. Dark is involved in, and Jim makes Will wait with him in the tree to find out the answer to that question.
What the boys see from their hiding place is beyond anything they could have expected. They watch as Mr. Cooger, on the carousel, grows younger as it turns backwards. He gets off as a twelve-year-old boy. Mr. Cooger scares Will and Jim when he is a grown man, but the thought of him inside the body of a young boy terrifies them. They see the impossible happen, and they come to the conclusion that their only choice is to follow after Mr. Cooger and see what else happens. Bradbury's story has gone from charting the wonder and adventure that thirteen- year-old boys find in the everyday events in life to something far greater. It is now clear that Will and Jim are involved in an adventure that goes way beyond anything they have ever seen before. Although the story has left reality behind, the boys themselves still act in a plausible manner. This is the first of many times in the book that Bradbury weaves together the improbable and the probable, ultimately questioning whether the real world is as clearly distinguishable from fantasy as it appears.