Escape From Horrorland (Goosebumps Horrorland #11)

Not long ago, Luke and Lizzy Morris dared to spend one day at HorrorLand, the terrifying theme park where nightmares come to life. They thought that NOTHING could lure them back, but their travel plans are about to change.... Who--or WHAT--is summoning ordinary kids to HorrorLand and trapping them there? Luke and Lizzy are determined to find out. They've gathered every clue, and they even launched their own secret website at EscapeHorrorLand.com. This time, Luke and Lizzy are prepared to face any danger--and any villain. Or so they thought...