Someone is causing havoc in Nod's Limbs - and it's not Edgar and Ellen! The construction of Mayor Knightleigh's new hotel is being blocked by mysterious acts of sabotage. The twins are determined to unveil the saboteur (after all, they want in on the destruction!) and descend into the vast maze of tunnels under town, where they unearth a secret laboratory. They also find Eugenia Smithy, the daughter of a rival construction company turned down for the hotel commission. The twins agree to band together with her to sabotage the construction - watch out Mayor Knightleigh!