Ash is traveling through the forest on his way to Oreburgh City, where he hopes to earn his first Gym Badge in Sinnoh. But first he's helping Starly practice using Aerial Ace, a process that doesn't go entirely smoothly. Our heroes also catch the attention of Rosebay, a woman who monitors the Pokémon that live in the forest. Lots of Pokémon have been disappearing lately and she's not sure why, but it doesn't take long for Ash and his friends to decide they should help her out!
Meanwhile, Team Rocket have set up a trap in the Valley Path, an area which Flying-type Pokémon often pass through. All it takes some netting and soon Team Rocket is happily snagging lots of avian Pokémon for their Boss. When Ash sends Starly out to look for clues, Starly is swept up by Team Rocket's criminal plans as well—but Starly isn't about to sit back and wait to be rescued! Jessie and James leave Meowth to guard their ill-gotten Pokémon, and Starly is ready to stage a jailbreak together with help from a captured Hoothoot.
Hoothoot hypnotizes Meowth into letting the Pokémon go, but when Meowth snaps out of its trance, it calls for backup from Team Rocket's other Pokémon. However, Ash and his friends came across a Pidgeot trapped in Team Rocket's net and realized what was going on, and they show up looking for Starly! Jessie and James return and try to stop our heroes, only to discover that Brock's Bonsly can use Mimic to send their Pokémon's moves right back at them. Then Starly evolves into Staravia and pulls off a terrific Aerial Ace—which is also the term that describes Team Rocket as they go blasting off again. The trapped Pokémon are freed, Rosebay is happy, and now it's onward to Oreburgh City!