Ash and co. are finishing up their break in the middle of an open field. When all the Pokémon are done eating, Ash, Dawn, and Brock return their Pokémon back into their Pokéballs. Before they leave, Pikachu tells Ash that Turtwig is missing. Brock says that he saw Turtwig head into the woods. So Ash and co. head into the woods and call out for Turtwig. Turtwig runs out from the bushes and approaches Ash. It tugs on Ash's leg. Ash and co. follow Turtwig to a mountain. Trapped on the mountain is a Pokémon. Ash calls out to the Pokémon and tells it not to worry.

Ash and co. arrive at the top of the mountain. Ash is strapped to a rope. Brock has part of the rope wrapped to a tree, and he is holding the other half. Ash slowly climbs down the mountain so that he can bring the Pokémon back up to safety. Dawn tells Ash to be careful when climbing down since he almost fell. When Ash arrives on the ledge of the mountain, he tells the Pokémon that everything will be okay and to trust him. Ash extends his hand out to the Pokémon. The Pokémon bites Ash's hand. Dawn tells Ash that he has to first calm the Pokémon down because it is scared. Ash knows that Dawn is right, so he calls Pikachu down to help him. Pikachu tries to convince the Pokémon that Ash is there to help. The Pokémon finally trusts Ash and he gathers into Ash's arms. Then Dawn and Brock pull Ash up to the top of the mountain.

Ash introduces himself to the Pokémon. Brock notices that it is a Hippopotas, and Dawn looks it up in her Pokédex. Hippopotas is still scared from the fact that it almost fell off the mountain. Brock pulls out a snack for Hippopotas. Hippopotas tries some of Brock's food, but it doesn't really like it. It heads over to a tree with fruit on it. Ash takes one of the fruits off the tree and feeds it to Hippoptas. The Pokémon eats it in one bite. Ash and co. is glad that Hippopotas is safe. They say their goodbyes to Hippopotas and begin to continue their way towards Hearthome City.

While walking, Pikachu notices that Hippopotas is following them. Ash thinks that Hippopotas wants to be with him. Hippopotas shows its smile. Suddenly, Ronda from the TV show appears and finds out that Hippopotas has been found. Ash recognizes Ronda. Ronda recognizes Ash and co. too. Ronda tells them about how Hippopotas love to live in dry pieces of land and cover themselves in sand. Then when the season begins to change, the Hippopotas herd departs their land in groups. Ronda believes that the Hippopotas that Ash rescued got separated from its herd. Ronda has a strong sense to where the Hippopotas herd is headed to. Ash wants to find the herd and bring Hippopotas back to its family. Hippopotas is excited to hear that.

So Ash and co. begin to run towards the direction of the herd, and Ronda and her co-workers runs after them. Suddenly, they fall into a hole. A rope drops down and snatches Hippopotas. It is Team Rocket. They are in their balloon making their escape with Hippopotas. Hippopotas struggles to get free. It releases a huge bubble from its mouth, and it hits Meowth. Ash and co. climb out of the hole. Ash sends out Turtwig. Turtwig uses Razor Leaf and cuts the rope. Hippopotas begins to fall, and Ash catches it. Hippopotas releases another bubble from its mouth, and this time it hits Brock and Jack, one of Ronda's co-workers.

Team Rocket is floating in the air in their balloon. Meowth has gone off to sleep. James says that it is Hippopotas' Yawn attack that placed Meowth to sleep. James suggests that they give Hippopotas to the boss as a present. James tells a few stories about how the boss would love it. While Ash and co. are walking, Brock suddenly falls over onto the ground and sleeps. Dawn explains that Brock was hit by Hippopotas' Yawn attack, so there is nothing they can really do. Suddenly, they see Team Rocket's balloon. Ash and Dawn decide to hide in the bushes. When they get there, they find out that they have left Brock behind. Croagunk, however, has Brock in its arms and drags him off to the side. Ash and Dawn thank Croagunk for its quick thinking. Ronda is angry that Jack is asleep because now she has to hold the microphone herself.

Brock finally awakens. He thanks Ash and Dawn for saving him from Team Rocket, even though Croagunk was the one who did it. Up ahead is a construction zone, so Ash and co. now have to find another way to the Hippopotas herd. Suddenly, a piece of fruit attached to a string floats towards Hippopotas. Hippopotas grabs the fruit, and Team Rocket pulls it up. Ash and co. demand that Team Rocket gives Hippopotas back, but they refuse to do that. Hippopotas uses its Sand-Attack on Team Rocket. Then it uses Sand Tomb, causing Team Rocket's balloon to crash. Hippopotas runs away from Team Rocket and back to Ash. Ash compliments on Hippopotas' great work. Finally, Ash sends out Aipom. Aipom uses its Focus Punch attack on Team Rocket, and they blast off again.

Hippopotas then uses its Yawn attack on Dawn. Seconds later, Dawn falls asleep, and Brock ends up carrying her up to a bridge. By the time they get to the bridge, Dawn awakens. They have to cross the bridge to get to the herd. Brock reminds Ash that Hippopotas is afraid of the water. Ash reassures him that everything will be okay. Ash and co. begin to cross the bridge. Suddenly, Team Rocket appears again, and they block Ash and co.'s path to the other side. Team Rocket takes out a net and uses it to capture Hippopotas. Ash jumps onto the net. The net breaks, and Ash and Hippopotas fall into the water. Brock sends out Croagunk. It uses Poison Sting on the balloon, and Team Rocket blasts off again.

Ash managed to find a rock that extends out of the water. Hippopotas is on top of the rock. It is very scared and a bit wet. Dawn sends out Buizel. Buizel heads towards Ash and Hippopotas. It takes Hippopotas and swims to shore. When Ash gets to shore too, they all wrap Hippopotas around in a blanket to help dry it off. Dawn thinks that Hippopotas is sick from the water. Brock looks in his guide book and notices that there's a Pokémon Center nearby. So they rush Hippopotas there. Nurse Joy does a checkup on Hippopotas and reports that it will be fine after a long rest. They place Hippopotas in a box of sand so that it can rest. Nurse Joy is worried that she might not have enough sand, so Ash and co. run out to find some. Ash sends out Staravia to search for sand. Staravia finds a huge area of sand. Ash and co. start to shovel a lot of the sand in a bag. When they are done, they head back into the Pokémon Center.

The sand is placed in the box where Hippopotas is in. Hippopotas is soon healed thanks to the sand. Nurse Joy comes out with a bowl of food for Hippopotas. When Hippopotas is feeling all better, Ash and co. set out on the road again to find Hippopotas' herd. While they are walking, they notice two people selling sand. These people claim to have the best sand ever. Hippopotas uses its Yawn attack on the girl. The girl takes out a bag of the sand for Hippopotas to try. When Hippopotas walks near it, the girl stuffs Hippopotas in the bag and runs. It is Team Rocket again. Team Rocket says their motto. In the middle of the motto, Jessie falls asleep. Hippoptas runs out of the bag to Ash.

James sends out Cacnea, and Ash sends out Turtwig. Cacnea starts the battle off with a Pin Missile attack. Turtwig dodges the attack and then bites Cacnea. Then Turtwig uses Razor Leaf, followed up with a Tackle. Then Pikachu uses its Thunderbolt attack, and Team Rocket blasts off again.

Ash and co. continue to walk along the road. Brock looks at the map and says that they should be really close now. Soon he spots some tracks that were left from the herd. They follow the tracks, but they don't see the herd anywhere. Hippopotas lets out a loud cry. Suddenly, a few Hippopotas emerge from underneath the sand. Ash sets Hippopotas on the ground so that it can meet all its friends. Then Ash throws one last piece of fruit at Hippopotas, and it eats it. Ash and co. say their goodbyes to Hippopotas. Before they can leave, Hippopotas uses its Yawn attack on Ash, putting him and Pikachu to sleep. Dawn thinks that it is a way for Hippopotas to say thank you, since Ash has done so much for the Pokémon. So Ash and co. continue their journey towards Hearthome City.