Matt Daniels battles a mysterious substance called Monster Blood that makes things grow, and then visits HorrorLand amusement park, where some of his friends disappear.
"What should Carly Beth be for Halloween this year? Terrified! Late at night, an ugly green mask is mysteriously calling out to her, and ugly green masks don't like to be ignored" (publisher).
Robby creates his own comic strips so he can freak out his friends and family, but now his favorite character Dr. Maniac, a villain with a wicked grin and evil superpowers, is on the loose in the real world!
Abby and Peter pay a visit to their Uncle Jonathan, who seems very knowledgeable about Egyptian mummies, but they become suspicious at the strange sounds coming from a room inside his house, and their fears continue as they are invited to HorrorLand.
When Michael sneaks into his superstitious teacher's house to play a prank on her, he discovers that she is an evil alien hatching up a brood of monsters to take over the Earth.
Boone and Heather are going to summer camp, with man-eating snakes and disappearing campers. Things get worse when Boone joins eleven other guests at HorrorLand because something's wrong with the bumper-car ride called the R.I.P.P.E.R.
"Jillian and Jackson freak out when they suddenly can read people's thoughts. But the trick turns to terror when the twins are stalked by a strange scientist who wants to know exactly what's on their minds. Will the twins ever lead normal lives again? Not in HorrorLand they won't. There are free meals, free games, and free falls down the Doom Slide. Someone's watching their every step. But is she friend or foe?"--Page 4 of cover.
"Lizzie and Luke have uncovered secret information about the freaky amusement park. Lizzie wants to help the others, but since the twins don't trust her, they're all in a deadlock. Did someone say DEAD? A trip through the Hall of Mirrors lets the kids escape HorrorLand and enter Panic Park. Safe at last! Or are they? Why are there no exits? What's in the Tunnel of Hate? Have they been tricked again?"--Page 4 of cover.
Twelve-year-olds Andy and Marnie, having enjoyed a day at HorrorLand and received a gift souvenir from the Chiller House, take home a wish-granting hound's tooth which is supposedly haunted and soon learn that nothing is ever really free.
Sam Waters is desperate to have a pet. But his parents say that first, Sam must prove he's responsible. So he takes an after-school job in a pet store called Little Shop of Hamsters. To his horror, Sam soon finds that cute, little hamsters can become very uncute monsters. Suddenly, Sam isn't fighting for a pet--he's fighting to survive!
Jessica and her best friend, Ryan, find the perfect HorrorLand souvenir--a two-headed coin with mysteriously dark powers. After an unlucky flip of the coin, they find themselves in a strange land being chased down by angry guards. HorrorLand was scary but this is much worse. Will they be able to escape?
When Marco finds a rare edition of the Ooze comic book at HorrorLand, he finds that many monstrous collectors would do anything to get their hands on the comic.
Andy, Sam, Jessica, Meg, Marco, and Ray are trapped by Jonathan Chiller, who expects payment for the rare HorrorLand souvenirs they have taken by playing his deadly game.