On their way to the Castelia City Gym for Ash’s next Gym battle, our heroes encounter Gym Leader Burgh, who says he can’t answer Ash’s challenge until he figures out what’s been bothering his Bug-type Pokémon. Ash and friends pitch in to help him investigate. Together, they discover a Venipede in distress, and of course Ash wants to help it!

Upon further investigation, the gang learns that the whole city is being overrun by a gigantic colony of angry Venipede! The townspeople are in a panic, and the mayor of Castelia City declares that something must be done at once. Ash’s rival Trip is also in town, and he suggests that battling the raging Venipede is the only way to stop them. Burgh counters with a plan to round them up and herd them into the city’s Central Plaza until Professor Juniper can figure out what’s going on.

Working together, the three Trainers find every last Venipede and bring them all to the plaza. Soon, Professor Juniper discovers an unusual energy emanating from the Desert Resort, just outside Castelia City! She concludes that the underground energy flow must be what disturbed the Venipede. The professor and Officer Jenny take off to find out exactly what’s happening in the desert, while Burgh stays behind to look after the Venipede—and Ash’s thoughts turn to his next Gym battle!