The cover illustration depicts a zombified hand bursting out of a grave holding a torn bag of candy. A zombified leg is sticking out of the grave next to it.
Scott Harmon would be the kid who is most afraid of everything at his school. That is, if it wasn't for his best friend, Amanda Gold. They really don't have it easy. Scott's younger sister spends her time frightening them. She'll do whatever it takes to get them to scream.
Scott and Amanda are also tormented by some neighborhood kids. But this Halloween, Scott and Amanda are determined to get over their fears, even if that means spending time in the creepy old house that everyone else says is haunted. And if Scott and Amanda can stop being so afraid, maybe they can even finally get some revenge...
Scott Harmon and his friend Amanda Gold are very easily frightened. Scott is so easily scared, even his nine-year-old sister, Rita, enjoys scaring him. At school, Scott is usually terrorized by a pair of twin bullies named Mickey and Morty Klass. Scott and Amanda have decided to visit a local haunted house in order to become less cowardly, which is located next to a graveyard. The two kids walk up to the door of the house but are interrupted by Mickey and Morty.
They drag Scott and Amanda away from the house and force Scott and Amanda to walk through the nearby graveyard. While in the graveyard Mickey and Morty's friend, Kenji Kuroda, scares Amanda and Scott by pretending to be a zombie. Once Kenji, Mickey, and Morty leave, Scott and Amanda decide they want revenge. Scott and Amanda both leave the graveyard. When Scott gets home, Rita informs him that the Klass brothers had filmed Scott and Amanda getting scared in the graveyard. The Klass brothers put the video on YouTube.
The next day at school, Scott attempts to pants Mickey but instead, Scott is pantsed by Kenji. The following Saturday, Scott and Amanda once again visit the haunted house. The kids sneak into the house and hear strange and worrying sounds. Right before Scott and Amanda leave the house, Scott sees a wooden box and takes it with him. Scott and Amanda run back to Scott's house and go to his room. Amanda warns Scott not to open the box he found, but Scott feels uncontrollably compelled to open the box. When he opens it, a purple mist comes out. They look inside of the opened box, and they find a red scarf. Upon closer inspection, they find that the scarf is wrapped around a wooden mask. Scott says that the mask looks like a death mask.
The mask has a small face protruding from its forehead. Rita and Amanda both tell Scott that he should try on the mask, and Scott is unable to resist the urge to put the mask on his face. When Scott looks through the mask, everything appears distorted, as if underwater. Amanda leaves, and Scott goes downstairs for dinner. At dinner, Scott's mom has prepared very strange food: cow tongue, oyster soup, and slugs! His mom insists that the foods she has prepared are Scott's favorites. While Scott's mom is in the other room, Scott and Rita begin fighting. Scott wishes Rita had never been born, and she disappears in a puff of smoke. Then, Scott hears Rita's voice and he feels the mask being removed from his face. Scott was still in his room, Amanda hadn't left, and Rita was still alive. Scott hides the mask in his closet.
Scott goes downstairs for dinner, and his mom tells him that Aunt Ida will be visiting soon. The next day is school picture day. When Scott is walking to school, he is caught by Kenji, Mickey, and Morty. They drag Scott to the graveyard and throw him in an open grave. Scott gets covered in mud and has to go home to get new clothes. Later in the day, when Scott has returned from school, he finds an old woman with white hair and a gold tooth digging through his dresser. Scott assumes this must be Aunt Ida. The woman says that she has to go, so she leaves. Scott's mom comes home and Scott tells her about Aunt Ida, but Scott's mom says that Aunt Ida wouldn't be able to visit.
When Scott goes to sleep, he dreams that the old lady returns to his room. In the dream, the woman is searching through Scott's room and turns into a crow. The next morning, Scott finds a black feather in his room. Later in the day, Scott, Amanda, and Rita go back to the haunted house. They are preparing to scare the Klass brothers and Kenji. Scott says that he is going to invite the bullies to a very scary Halloween party. Scott is planning on making the house look haunted by using props and recordings of scary sounds. When the three bullies are all in the house, Scott is going to lock them in. Once he locks them in, Rita, disguised as a ghost, will come out and scare the bullies. After Scott, Amanda, and Rita finish decorating the abandoned house, they are notice that the window that they had opened earlier was now closed. The three of them hear a voice asking them to stay and they run away. While running away from the house, they are startled by Kenji, Mickey, and Morty. Scott dares the three bullies to come to the old abandoned house on Halloween for a party.
On Halloween night, Scott and Amanda are at the haunted house. The two friends have already finished decorating the house earlier in the week. Rita is hiding upstairs. Kenji, Mickey, and Morty come over dressed as skeletons. All five kids downstairs hear a ghostly scream from upstairs. Scott and Amanda don't remember planning it. Then, dozens of ghostly figures begin floating down the stairs and disappearing. They see a skeleton outside and hear more unexpected sounds. Kenji, Mickey, and Morty eventually admit that they had removed Scott's scary surprises and replaced them with different scares.
However, all the kids become scared when they see the death mask float downstairs by itself. The kids become surrounded by a purple mist and an old lady, the one that had been in Scott's house, approaches them. The woman says that her name is Lillian. Scott apologizes for taking the mask, but Lillian says that Scott and the others must keep her company forever. She also says that she was trapped in the mask and Scott freed her by opening the wooden box. When Mickey and Morty try to escape, Lillian sets their ears on fire. Lillian's spirit is connected to the mask, so in order to be completely free from it, someone else must "live" inside of the mask.
When Lillian tries to put the mask on Scott, Scott instead grabs the mask and puts it on her. The ghost disappears and the five kids leave the house. Then Scott and Amanda remember that Rita is upstairs. Scott goes back to the house. Scott can't find her and rushes home. He finds Rita in his house and asks her how she escaped, but she says she didn't. Scott then sees that his sister has a gold tooth, which looks just like the one that Lillian had.
The pre-release cover was revealed on Schoastic's website in December 2014, seven months before the book was officially released. The artwork was radically different compared to the final. It featured changes such as a monochrome color scheme, a zombie-like head emerging from the grave instead of a hand, with a ribbon-like object swirling around the grave. Additionally, the grave on the left had a jack-o'-lantern next to it instead of a foot emerging out of it. The house's design was also different.
- The title of this book is a reference to "Trick or Treat", a phrase people usually say on Halloween.
- This title is strikingly similar to the Give Yourself Goosebumps: Special Edition book, Trick or...Trapped!.
- Similar to the previous Most Wanted: Special Edition book, The 12 Screams of Christmas, the "Welcome. You Are Most Wanted." section is not present in this book.
- The "Contents" page of certain printings of this book mistakenly lists Night of the Puppet People as the fourth Most Wanted special edition. Night of the Puppet People is the eighth book in the Goosebumps Most Wanted series.
- Scott's father was mentioned by name in the book: Sid Harmon.
- Amanda has a dog named Curly. The name may be an allusion to the former Goosebumps mascot, Curly the Skeleton.
- This book references Fiat, iPod, iPad, YouTube, Instagram, Marvel, Thor, Wolverine, Guardians of the Galaxy, Ant-Man, Hulk, Captain America, Wonder Woman, Hello Kitty, and UPS.
- Scott shares a last name with Jack Harmon, the protagonist of Don't Scream!