Continuing to the next town, Ash and friends are travelling down a forest path. Dawn goes to drink out of her water bottle, and realises that it is empty, so goes to fill it up at a spring further back, while Ash and Brock wait. There she starts to fill her bottle up from spring water trickling down a large rock. Suddenly an Aggron emerges from the top of the rock and fires a Hyper Beam at her. When she tries to run away she slips and falls in a river and gets carried downstream. When she gets out of the water, she and Piplup look up Aggron in her Pokédex.
Meanwhile Brock and Ash, who are looking for Dawn, as she has been a while, arrive at the spring. They notice Dawn's water bottle on the ground and when they investigate find her shoeprint on the rocks by the edge of the river, deducing that she must have fallen in. They start to worry for her safety when suddenly Aggron appears and attacks them. Ash and Brock make a hasty retreat, then Ash asks Brock why Aggron attacked. Brock walks up to a rock and examines it, saying that the rocks around here must have a high iron content. Ash suggests that Aggron could be defending its territory. Ash sends out Gliscor and {{AP|Staraptor|| to look for Dawn.
Elsewhere Dawn is running to warn the others about the Aggron and Team Rocket are in a bush, they suggest attacking Dawn while she is alone. They release a smoke bomb and then perform their motto. Jessie attempts to capture Piplup with a lassoo, but when it misses she sends out Yanmega. Piplup uses BubbleBeam, which Yanmega avoids, before countering with AncientPower. Piplup dodges and then hits Yanmega with Whirlpool. Suddenly Dawn runs away with Piplup, surprising Team Rocket with James saying "Retreating's not the twerpette norm!". They turn around to find Aggron behind them. It uses Hyper Beam and they run, whilst Aggron is firing. They then seek refuge in a bush. James look up Aggron on his cards.
Staraptor and Gliscor are flying over various areas of the forest calling out. Meanwhile Ash and Brock are calling for Dawn and her Piplup. Dawn runs into a clearing and sends out her Pachirisu and her Buneary. She tells them to use Ice Beam and Discharge respectively in hopes of Ash and Brock noticing, but Team Rocket and Aggron notice, the latter of which appears near the clearing. They all run away. On a nearby ledge, Team Rocket laugh at Dawn and her Pokémon running away from Aggron, hoping that they will get tired out.
Dawn's Pokémon stop suddenly and Dawn realises that she is at the side of a steep cliff. With Aggron just behind her, she decides she has no choice, and so sends out Mamoswine. She tells it to use Take Down, but it goes to sleep instead, so she feeds it a Poffin. Then Mamoswine is hit with a Hyper Beam, which enrages it It retalliates by charging at Aggron, but is hit with a powerful Double-Edge. Mamoswine uses Ice Shard, but Aggron blocks it with Ice Beam. Aggron then uses Double-Edge again, and Mamoswine is thrown to the ground, making the ledge collapse, sending Dawn and her Pokémon falling. Team Rocket then get chased by Aggron. When at the bottom, Dawn brushes her self down and makes sure her team is okay, but notices Mamoswine's leg is badly hurt. She tries to return it, however she has lost Mamoswine's Poké Ball.
She realises Aggron could return at any minute and she decides to hide Mamoswine. She sends out Ambipom and her team can make a bed for Mamoswine; Ambipom uses Focus Punch on some branches, whilst the others collect the fallen foliage. She makes Mamoswine a bed, then asks Mamoswine to move. It does, with the rest of her team helping it. They then cover Mamoswine with more branches to hide it from Aggron and Team Rocket.
Dawn asks Mamoswine whether or not it is in pain, then remembers what Brock told her when Pachirisu was sick in Doc Brock, that she must remain calm. After comforting Mamoswine she and her team find some small plants which Brock told her have healing powers. She squeezes the fluid from the leaves onto the woulnd and then bandages it. She then asks Piplup to use Whirlpool in a bucket, but must remind Piplup that it needs to be very small. Buneary freezes it with Ice Beam and Dawn places the ice in a bag, and puts it on top of the bandage. They go to find some Oran Berries, which Dawn asks Ambipom to pick. She then notices some fruit and tells her to collect that as well.
Ash and Brock are standing on the cliff where Dawn fell, wondering where she went. suddenly Pikachu finds Mamoswine's Poké Ball. At the bottom of the cliff, Team Rocket appear, but don't notice Dawn and her Pokémon. Dawn hides and Team Rocket notice a 'behemoth' tree, which also happens to be the tree Dawn and her Pokémon are hiding behind. They decide to spend the night there so they will be safe from Aggron, so Dawn asks Ampibom to scare Team Rocket away. Ampibom gets a boulder and starts bashing it against the ground by some bushes behind Team Rocket, making them run away. Aggron turns up, so Pachirisu runs into a bush and starts to make it rustle, luring Aggron away.
Ash and Brock are camping in a cave. Brock comments that he thinks the Pokéball is Mamoswine's, and as it is empty Mamoswine must be out. All of Dawn's Pokemon are sleeping against Mamoswine, but Buneary wakes up, so it hops over to Dawn, who asks it to use Ice Beam, as the ice on Mamoswine's leg had melted. They all then fall asleep next to Mamoswine.
The next morning the search resumes, and Team Rocket attack Aggron with their 'Giga-Golem', which is knocked back by Aggron's Hyper Beam. They retaliate by firing a rocket-propelled boulder, knocking Aggron over. This only angers Aggron, which counters with Double-Edge making the mecha roll into the tree where Dawn is hiding. The impact makes the leaves to fall off Mamowine. They then want to attack Mamoswine, but Dawn refuses to let them do so, standing in their way. Staraptor sees this and flies off to get Ash.
They then fire the 'Boulder Holder', which spirals towards her, but Mamoswine steps in and stops it with its tusks, sending it back at Team Rocket knocking them back. Ash and Brock arrive at the scene. Mamoswine uses Take Down on the mecha, knocking Team Rocket out of it. Pikachu runs towards them, so Jessie sends out Yanmega. Pikachu dodges its Steel Wing and AncientPower, and then blasts Team Rocket off with a Thunderbolt. Aggron appears and Mamoswine throws Dawn and her Pokémon onto its back. Mamoswine, following Dawn's commands, blocks Aggron's Double-Edge and Hyper Beam with its tusks, before countering with Ice Shard and AncientPower, making Aggron run off. Ash hands Dawn Mamoswine's Poké Ball which Pikachu found. Dawn then mentions the food Ambipom collected, but Mamoswine is already eating it. The episode then ends with Brock saying, "The more things change, the more they stay the same", then Dawn says, "at least we don't have to store leftovers". Then the group all laugh.
