As our heroes travel through the forest, Dawn stops at a spring by a river to refill her water bottle. A wild Aggron suddenly attacks her, and she falls into the river; by the time she makes it back to shore, she's been separated from her friends. When Ash and Brock go to the spring to look for her, they're attacked by Aggron too! Dawn searches for her friends, but all she finds is Team Rocket. Team Rocket wants to swipe Dawn's Piplup, but Dawn cuts the encounter short and runs for it as soon as she sees Aggron coming.

After she's in the clear, Dawn tries to signal her friends by having Buneary and Pachirisu use their attacks. That only ends up attracting Aggron's attention again! Dawn tries to battle Aggron with Mamoswine, but Mamoswine ignores her commands. Aggron's attack causes both Dawn and Mamoswine take a hard fall off a cliff. Now Mamoswine's leg is injured and Dawn lost her Poké Ball in the commotion, so she shifts Mamoswine under a tree and camouflages it with branches. Then she and her Pokémon all pitch in to care for Mamoswine's injury.

Dawn hears Team Rocket approaching, so Ambipom scares them away by pretending to be Aggron. Soon after that, the real Aggron approaches! This time, Pachirisu distracts Aggron to lead it away from Dawn and Mamoswine. Dawn and her Pokémon camp out under the tree but the next day, Team Rocket is back in the area to challenge Aggron with a brand-new Golem robot.

Aggron knocks the robot right into Mamoswine's tree, and Team Rocket spots the injured Pokémon. It could be a valuable steal, but Mamoswine is all healed up and it knocks Team Rocket right out of their robot! Ash and Brock have found Dawn's missing Poké Ball and they arrive on the scene just in time for Pikachu to blast Team Rocket into the sky. Then Mamoswine and Dawn battle Aggron, with the Pokémon and its Trainer now fighting like a real team. And once they send Aggron packing, Mamoswine can get back to its favorite pastime: eating!