Ash discovers and catches a Caterpie—his first Pokémon capture! Though Ash is excited, Misty is grossed out by Bug-type Pokémon, so she is repulsed by its attempts to be friends with her. At night, as Ash and Misty sleep, Caterpie shares with Pikachu its dream of evolving into a Butterfree.

The next day, Ash is able to capture a Pidgeotto after battling it with Pikachu. Before Ash can celebrate too wildly, Misty reminds him that his success is due more to luck than skill.

Team Rocket shows up to steal Pikachu—they realize that there's really something special about this Pokémon—and Ash vows to defend himself. Pikachu and Pidgeotto are weakened by Koffing and Ekans, so he reluctantly sends out Caterpie. To the surprise of Jessie and James—not to mention Ash—Caterpie's String Shot is able to defeat the Team Rocket Pokémon, including Meowth!

When Misty tries to make nice with Caterpie, it evolves into a Metapod. Could a Butterfree Evolution be far behind?