A towering crisis interrupts the twins' usual mayhem: The mayor is about to build his monstrous Knightlorian Hotel right next door! But as they try to halt construction, Edgar and Ellen encounter a new foe — an unknown prankster who's stealing their thunder (and their best schemes)! To stop the rash of copycat capers the twins must descend into the sewers, but what they discover there is stranger than anything they could have imagined. A mysterious journal, a secret laboratory, a villain's hideaway — there's a lot more than sewage running beneath Nod's Limbs!