It's Halloween and Mallory has a trick up her sleeve! Scheming Mallory and her reluctant sidekick Arthur have a Halloween misadventure involving nasty tricks, time travel and a sneaky cat. Mallory wants candy, as much as she can grab, and she’s prepared to play some tricks (and kick a pesky black cat) to get it. But when she and her reluctant sidekick Arthur tangle with the owner of a spooky old house, the trick is on them. In the beat of a bat’s wing, they’re a century back in time with a mission to find that slippery cat, or Mallory will change shape forever . . .