Abby and Peter are staying with Uncle Jonathan in an eerie old village. Their uncle knows a lot about Egyptian pyramids, and his living room even looks like an ancient tomb. Do other secrets lurk inside Uncle Jonathan's house? MUM's the word! Someone - or something - is inviting ordinary kids to HorrorLand and trapping them there. But they're not the only guests of the terrifying theme park where nightmares come to life. Slappy the Dummy, Monster Blood, and other vile villains have joined the terror trip, too. And HorrorLand is about to add one more old fiend to the guest list: a cursed mummy!