Ash and his friends visit a famous fishing spot that looks oddly abandoned. Ash still manages to hook a Crawdaunt, which he challenges with Corphish. But Crawdaunt wins and begins wrecking property until a woman named Tiffany chases it off. Tiffany explains that the lake was busy until a year ago, when Saridakis Industries wanted to fill in the lake and turn it into a spa. Tiffany wouldn't sell out, but Crawdaunt scared off all the fishermen and Pokémon.
Naturally, Ash and friends help her out. They track down Crawdaunt, which belongs to Mr. Saridakis himself! Team Rocket is there too, disguised as consultants so they can steal Crawdaunt. Tiffany confronts Saridakis, who says he didn't ask Crawdaunt to ruin the lake. But he'll battle Ash and Corphish tomorrow: if Saridakis wins, he gets the lake! He fell into the lake once when he was a boy and though he somehow survived, he's hated the place ever since.
To help Ash train for the battle, Tiffany's Granny Galea challenges him with her Vaporeon. By cleverly using the terrain, her Vaporeon is able to beat Corphish. The next day, Ash also has Corphish use the lake to its advantage while battling Crawdaunt. Except Team Rocket interrupts the match and steals Crawdaunt!
Ash and his friends stop them and rescue Crawdaunt, but in the commotion, Saridakis falls into the water. He's saved by none other than Granny and a Dragonair, who saved him back when he a boy, too. Saridakis realizes it'd be wrong to fill in the lake, and things return to the peaceful way they were as Ash continues towards his Battle Frontier destination.