In this spinoff to the New York Times–bestselling Goosebumps series, a tween is given monster blood, a mysterious serum that gives him strange powers. For an athlete like Matt Daniels, breakfast is the most important meal of the day. It's also the most dangerous. That's because somebody pulls a mean prank and adds gooey, green Monster blood to his cereal bowl. As if Matt's problems weren't big and slimy enough, he gets an invitation to HorrorLand. Can the Monster Blood help him in the terrifying theme park? Matt really begins to wonder once his friends start disappearing!