Hoping to find a place to stay for the night, our heroes visit an imposing manor. Instead, they're almost mistaken for thieves by Marble, a self-proclaimed Super-Duper Ace Detective who's also Officer Jenny's student. Matthew, the manor's owner, received word that the Bandit Beauties Three were coming to steal his treasure, and Marble promised to stop them. Despite her promise, she's secretly worried: her Luxray hasn't obeyed her ever since it evolved, and she thinks it's all because Luxray can't get its Electric-type moves to work.
As for the Bandit Beauties Three, they're none other than Team Rocket. After snatching Matthew's treasure, they try to make a getaway, only to fall into a pit trap! Matthew's manor is chock full of dangerous traps designed to catch thieves, except Pikachu and Luxray also fall down a pit trap while chasing after Team Rocket. Matthew shows Ash a secret passage that leads them to Pikachu and Luxray, but Marble accidentally springs another hidden trap, and this one is deadly!
Luxray uses its keen eyesight to locate the switch that deactivates the trap, much to Marble's delight. Then Team Rocket, busy digging out of the manor's basement, digs their way right into Ash and his friends. Pikachu uses a Thunderbolt that fills Luxray with electrical energy, allowing Luxray to finally use Charge Beam. The two Electric-type Pokémon help defeat Team Rocket, the manor's treasure is returned to its rightful owner, and Marble is once again friends with Luxray.