While seeking their lost dog, Piddle, twins Josh and Danny encounter their next-door neighbor, Petty Potts, a mad scientist whose SWITCH spray accidentally turns them into spiders.

On a trip to a pond with a local nature group, twins Josh and Danny accidentally eat a muffin laced with Petty Potts' SWITCH spray and are transformed into very stinky beetles.

While on vacation with their parents in Cornwall, twins Danny and Josh follow clues to another marble but find themselves trapped by the tide on a rocky island and the only way back is to use some pilfered REPTOSWITCH.

While seeking their lost dog, Piddle, twins Josh and Danny encounter their next-door neighbor, Petty Potts, a mad scientist whose SWITCH spray accidentally turns them into spiders.