On the road to Cyllage City, our heroes are forced to leap out of the way when a roaring truck barrels down on them, with Officer Jenny in close pursuit. When the dust clears, Ash and friends notice a cage that fell off the truck, and a weary Scatterbug that crawls out and collapses. They quickly scoop it up and take it to the nearest Pokémon Center, where Officer Jenny finds them—and tries to arrest Ash for being an accomplice in stealing the Scatterbug!
The misunderstanding is quickly sorted out. Officer Jenny explains that she’s on the trail of Dolan, a Pokémon smuggler who specializes in Scatterbug, Spewpa, and Vivillon. Because Vivillon can have wings of many different colors and patterns based on their native habitat, they’re highly prized by collectors, and Dolan takes full advantage of that.
When the Scatterbug they rescued evolves into Spewpa, Clemont notices something in its fur—it appears to be a transmitter, attached by the smuggler so he can keep track of his “merchandise.” They quickly develop a plan: one of them will wear the transmitter, plus a Spewpa disguise (provided by costume designer Serena) and act as bait, then Clemont will use one of his inventions to track the transmitter to Dolan’s secret hideout. Clemont’s Chespin is the closest to Spewpa’s size, so it gets the job!
Ash, Serena, Clemont, and Bonnie put the disguised Chespin in the cage and leave it for Dolan to find, while they and Officer Jenny hide nearby. And it works! Dolan arrives to claim his lost treasure, and then unwittingly leads our heroes to the cave where he’s keeping all the Pokémon he’s nabbed. When he catches our heroes poking around, he attacks with his Diggersby. Ash’s Froakie battles back—and then Spewpa leaps into the fray, evolves into a beautiful purple Vivillon, and uses its calming powers to take the fight right out of Dolan! Officer Jenny arrests him, and our heroes free all the captured Spewpa...who then evolve all at once, into Vivillon of many different patterns! They take to the sky in an amazing rainbow of colors, and our heroes’ journey continues.