Ian Barker's wanted a ventriloquist's dummy for some time, ever since the day he went to a doll museum and experienced a prank he thought was scary but clever. But while his wish comes true for his twelfth birthday, he didn't count on that dummy — who was left at his father's doll hospital a year ago — being Slappy, who's up to his usual tricks of trying to enslave his new owner and his family.
This book provides examples of:
- A Birthday, Not a Break: Pretty much the whole point of the story, it's Ian's birthday but since he gets Slappy for it, it all goes wrong.
- Abusive Parents: Downplayed, but Ian Barker's father drives him out to an abandoned museum in the middle of nowhere as a birthday "surprise" and hires actors to scare him — then laughs at Ian's resulting distress — though it was not out of pure malice. His parents also tell him and his sister to be nice to their cousins, because his cousins are going through tough times, even when they know that their cousins are being downright to mean to them. It is worse for Ian though, because no one believes him when Slappy comes alive and starts doing all the mean things in front of everyone, his father, sister, and cousins eventually believe him though.
- Be Careful What You Wish For: Ian has always wanted a dummy of his own, but the ones he gets is Slappy. The trope is even said word for word by someone during a flashback.
- Chekhov's Gunman: Early on, Molly is given a doll named Abigail is a present of her own. She is later brought to life too and puts Slappy to sleep.
- Clashing Cousins: This one has two for the price of one, with Vinny and Johny who are always picking on Ian and Molly.
- Early Installment Weirdness: Unlike the rest of SlappyWorld, this book is written in the third person.
- Heavy Sleeper: Vinny and Jonny's parents are impossible to wake up when they are asleep, which is why they don't hear Slappy going crazy one night.
- Here We Go Again!: Slappy is defeated but another evil doll demands the kids do her bidding.
- Losing Your Head: During their efforts to stop Slappy, Mr. Barker successfully removes his head. Unfortunately, this doesn't de-animate him.
- New Powers as the Plot Demands: This book gives Slappy a nosebleed that burns people.
- Same Plot Sequel: After Son of Slappy broke from the formula, this one sticks closer to it, with Slappy coming to life and doing his usual shtick.
- Sibling Rivalry: While it gets eclipsed by the rivalry with their cousins, Ian and Molly fight a lot, sometimes over small things like breakfast.
- Title Drop: Not the book title, but the series title. Slappy tells Vinny and Jonny "Welcome to SlappyWorld, boys!"