The cover shows the Blue Kerlew Hound in a park.
"It has powers you may not want to unleash."
In HorrorLand's eerie gift shop Andy finds a hound's-tooth necklace. The big tooth is yellow, has two sharp points, and, according to the shopkeeper, is said to grant wishes.
But Jonathan Chiller knows something else about the tooth. It's said to be haunted by the ghost of a huge hound. A ghost that's got a mouthful of sharp teeth—but wants this one back.
Andy Meadows and his cousin, Marnie Myers, are watching a show in HorrorLand. Andy is startled when a frightening clown, Murder the Clown, approaches him and tries to talk to him. The clown invites Andy and Marnie onto the stage. Murder the Clown says that they will be food for the zombie clowns. The show begins, but Andy and Marnie find themselves trapped when a large group of zombies begin closing in on them. The two kids are saved when Murder the Clown helps them escape. After successfully escaping, Murder the Clown assures the two kids that everything they saw was part of the show, but the kids remain skeptical.
The kids leave Murder the Clown and stumble into Chiller House, a HorrorLand gift shop. The kids meet Jonathan Chiller, the shop's owner. Andy sees a large and sharp tooth on display, but Chiller warns Andy that the tooth is too powerful. Chiller says that the tooth came from a Scottish dog known as the Blue Kerlew Hound. A legend states that the hound caused problems for the villagers, so the villagers enlisted the help of a sorcerer. The sorcerer cast a spell on the dog, and his spell caused the dog to lose one tooth and run away. The tooth could grant wishes, and the sorcerer used the tooth to become famous. However, the hound eventually returned, and it killed the sorcerer. Andy wants to buy the tooth. Before he takes it, he is warned by Chiller to keep the tooth dry. Chiller also hands Andy a small Horror statue, and he says that Andy can pay him the next time they meet.
Back at Andy's house, Marnie is eager to see the tooth in action. Andy wishes that his parents would take him out for dinner, and Marnie wishes that they will take her as well. The wish comes true, as does Andy's wish for his father to have a brand new Escalade. Andy wishes that his father will own a new Escalade. That night, he hears long howls outside of his window. The following Saturday, Andy goes to the mall. Andy is slightly distraught when he runs into Marnie, and Marnie wants to make more wishes. Marnie starts bugging him about the tooth, which causes Andy to wish that Marnie will stop talking about the tooth, and then she loses her voice.
Marnie grabs the tooth and undoes Andy's wish but in the process of grabbing the tooth, Marnie accidentally jabs Andy with the tooth, which causes a small cut on his chest. Marnie tries to make a wish, but when she does, a white light shocks Andy. The light causes him to go unconscious. Andy awakes a while later, and he sees two complete strangers and a little girl who claim that they are his parents and little sister. Marnie rationalizes that, because Andy made a wish while the tooth was wet, something terrible had happened. The people who claim to be Andy's family become progressively more annoying, and, in a moment of panic, Andy wishes that he could be ten-thousand miles away from them. Andy suddenly finds himself in a space capsule orbiting Earth.
Andy is impressed by the view and accidentally wishes that Marnie could see the view, so she appears. Marnie tries to take the tooth, but the tooth floats away because there is no gravity. In a struggle to get the tooth, the two kids bump into a control panel and cause the space capsule to start veering back towards Earth. Andy wishes that he could be back home, and he is teleported there. Much to his dismay, Andy looks outside and sees a huge cage around his house. He also sees many people looking in and gawking at him.
Andy goes outside and tries to talk with the people, but he finds that their voices are warped and impossible to understand. Andy also realizes that the people are not looking at him, they are instead looking at the large ape behind him. The menacing ape takes Andy's tooth necklace. Andy finds a beach ball and tosses it to the ape, causing the ape to drop the tooth into a puddle. Andy wishes that he were back home safely, but he is shocked again and he goes unconscious. Andy wakes up back at the mall, where he is greeted by Marnie and an old couple who been looking after Andy while he was unconscious, and they leave when he wakes up. Andy asks Marnie how she escaped the space shuttle, but she says that both of them had never left the mall. Andy sees Marnie wearing his tooth, but she insists that it has always been hers.
Andy goes home but he hears loud dog howls outside of his house. Andy goes online and finds that each wish made with the tooth sends a signal back to the dog that the dog can use to find the person who owns his tooth. Andy calls Marnie and tries to warn her, but she assumes that Andy is just jealous. During school the next day, Marnie reminds Andy that Congressman Boltz is going to be visiting the school later and deciding who would win the $500 essay writing prize. Andy is excited by this because his teacher tells him that his essay is the best. Later that day, Congressman Boltz announces that Marnie won. Andy knows that she cheated.
When Andy gets home, he sees the bruise on his neck that Marnie had caused when she tried to take his tooth. Andy realizes that she likely lied to him in order to get his tooth. Andy hears more howling outside and simultaneously devised a revenge strategy. On Saturday, Andy convinces Marnie to help him make an arcade cabinet. The two go to Andy's hound and begin working on the cabinet in the garage, and they leave the garage door open. Both Andy and Marnie hear the ghost dog howl. Since the garage door is open, nothing stands between the kids and the ghost dog when they see it approaching. As the dog draws nearer, Andy tells Marnie to give the dog her tooth unless she wants the dog to attach. Marnie admits that the tooth rightfully belonged to Andy. Andy reveals that the dog was actually his neighbor, Mr. Murphy's dog, Jack, painted blue, and he had tricked Marnie into admitting that she had lied.
Andy also reveals that his neighbor's dog had been that dog that was barking all night, not the Blue Kerlew Hound. Marnie apologizes for taking the tooth. Suddenly, Andy realizes that the dog he's looking at is not Jack, but in fact, the Blue Kerlew Hound. Jack looks into the garage but doesn't enter and then hurries out of sight, whimpering. The ferocious Blue Kerlew Hound slowly approaches. Andy tries to wish the hound away, but nothing happens. Andy wishes instead for invisibility in order to escape. The kids run into Andy's house, but Andy realizes that he dropped the tooth in the garage. Andy has to go back to the garage and sneak past the Blue Kerlew Hound. Andy uses the tooth to wish to be visible again. Andy then decides to simply return the tooth. Andy throws the tooth outside of the garage. Marnie comes out of hiding, and, when Andy looks back, the ghost dog is gone.
Mr. Murphy comes by for his dog and Marnie tells him that Jack is blue because they were making a video about a weird dog. Back at home Andy hears howling again. At first, he thinks it's Jack, until Marnie calls him and tells him that she found the tooth on the driveway and had taken it with her when she went home. Marnie agrees to share the tooth with Andy.
Andy was listening to the howling when suddenly, he sees the miniature Horror, the figurine that Andy had received from Jonathan Chiller, glowing. Andy feels drawn towards the small Horror, and suddenly he realizes that he has been teleported back to Chiller's shop. Andy is greeted by Jonathan Chiller, who is smiling ominously. Chiller welcomes Andy and tells him that it is time for Andy to pay for his gift.
- The concept of a ghost dog was previously used in The Barking Ghost
- This book references the Cadillac Escalade, Jeep, Scrabble, and Google.
- With the exception of spin-offs, this is the 100th main series Goosebumps book written.
- At one point, Andy's parents are playing scrabble and dad claims there is no such word as "fleg". Fleg was the name of one of the Beasts in The Beast from the East
- Andy's neighbor is named Mr. Murphy. There was previously a Mr. Murphy in Monster Blood II.