As Hapu and her Golurk tend to her radish farm and feed a trio of Sensu Style Oricorio, Professor Kukui, Ash, and his classmates arrive at the Seafolk Village port on Poni Island and meet up with Nurse Joy, who will be supervising them for the next few days. Kukui brings everyone's attention to their personal research projects and asks them to clarify their chosen topics. Sophocles says that he hopes to evolve his Charjabug at Vast Poni Canyon, Kiawe wants to train at Poni Wilds, Mallow is set on sourcing some Poni radishes for a new dish for Aina's Kitchen menu, Lana wishes to catch up with Ida, Lillie expresses her plans to study Poni Island's Pokémon, and Ash wants to challenge the Poni Island grand trial. Upon hearing Ash's intentions, Kukui informs him that Poni Island doesn't have a grand trial because there is currently no island kahuna. Sophocles explains that the former kahuna recently retired due to his old age. Kukui offers Ash a chance to battle him, but Ash instead decides that he will take on Tapu Fini. Afterwards, Kukui boards the ship back to Melemele Island.
Ash and the others set off to explore Poni Island and reach the Ancient Poni Path. Rotom spots a Golurk working the fields and scans it into its database. Mallow is thrilled to see Golurk harvest a Poni radish, which is known for their extreme length. Ash decides to help, and as he prepares to climb the picket fence, he hears a voice telling him to stay out before it commands Golurk to use Flash Cannon. The attack sends Ash and Pikachu hurtling away, but Tsareena manages to stop their momentum. Hapu reveals herself to the group and challenges them, assuming they are radish thieves. Ash accepts the challenge and has Pikachu use Quick Attack. However, Hapu says Quick Attack won't work because of Golurk's Ghost type. However, Pikachu strikes Golurk's leg with Iron Tail, causing the giant Pokemon to fall into a kneeling position. Hapu takes note of Ash's strategy and admits that it was clever under her breath. Ash has Pikachu go in for another Quick Attack and Iron Tail combination, but Golurk grabs Pikachu's tail and slams him into the ground. Pikachu is then knocked out by Golurk's High Horsepower. Hapu warns Ash's group to not return and steal her crops before walking off with Golurk and her Mudsdale.
Ash and his friends return to the Pokémon Center, and Pikachu makes a swift recovery thanks to its treatment. Joy overhears Ash and Kiawe's conversation about the Golurk Trainer they met, and she adds that the girl's name is Hapu. Nurse Joy explains that Hapu prefers to live alone, and while her parents live close by, she is deeply attached to her grandfather Sofu's land. Kiawe recognizes the name and claims that his grandfather was friends with Sofu. Joy adds that Hapu grew up around adults, and this contributed to her stubborn determination to win. Lillie is still unsure as to why they were called radish thieves, and Joy replies that Hapu has recently been struggling with a series of thefts. Mallow is keen to taste some Poni radish, and luckily Joy has some remaining. Everyone takes a bite, but Ash, Kiawe, Sophocles, and Lillie finds it too spicy, while Lana, Mallow, and Tsareena enjoy the taste. Then, Marowak takes a bite and finds it tolerable, much to Kiawe's surprise. The rest of the Pokémon try the radish and all but Sandy and Charjabug finds the radish too spicy. Joy admits the radishes are an acquired taste, but Hapu's produce is particularly good. Meanwhile on Hapu's property, Hapu contemplates Ash's odd decision to send out Pikachu against her Golurk.
Soon, Ash and his friends split up to do their own activities; Lana is going fishing before catching up with Ida, Lillie and Mallow decide to explore the Seafolk Village markets, Kiawe and Sophocles decide to do more training while Ash is set on locating Tapu Fini. Hapu looks out at the ocean and sets off on her Golurk to do a patrol after noticing that the sea is particularly still. Ash soon reaches Poni Beach, hoping to find Tapu Fini, but he instead finds a group of Oricorio. Suddenly, someone throws out a radish on a string and it immediately attracts one of the Oricorio. The Team Skull trio, Rapp, Tupp and Zipp, are then revealed to be the culprits and have already netted themselves several Oricorio. Tupp plans to have the Oricorio perform as dancers to the entrance of Team Skull Paradise. The trio is surprised to see Ash and go on to explain that they are on Poni Island to create Team Skull's Paradise. Tupp declines Ash's demands and the trio then sends out their Salandit, Zubat, and Garbodor against Pikachu.
Hapu spots the confrontation from the air and intervenes before things get heated. She then spots some of her stolen radish and turns to Ash for answers. Ash proclaims his innocence and explains that Team Skull were trying to catch the Oricorio. Hapu then notices the loot bag and tells Team Skull that they are in need of punishment. Tupp and his teammates remain defiant and belittle Hapu for her short stature. Hapu then calls on Mudsdale for assistance, and its arrival causes Team Skull's Pokémon to walk backwards. Ash insists that it is his battle, but Hapu cuts him off and declares that she is capable of handling the situation on her own. The Skull trio command their Pokémon to attack Mudsdale. The direct hits instead help activate Mudsdale's Stamina Ability, which increases its defenses. Mudsdale's High Horsepower attack defeats the Team Skull trio in one blow. Suddenly, the Team Skull trio's boss, Admin Plumeria, arrives on the scene. She is unimpressed when Tupp admits that they were trying to capture the Oricorio to have them dance at the Team Skull Paradise. Zipp, Tupp, and Rapp follow after Plumeria and ignore Hapu entirely.
Ash releases the Oricorio from the loot bag, and the wild Pokémon are happy to be free and reunited. Hapu apologizes for mistaking Ash for a radish thief and asks for his forgiveness. Ash is not fussed and then asks Hapu for a battle. Hapu, however, abruptly declines and she recalls Mudsdale before heading for home. Ash declares that he won't give up on the rematch, causing Hapu to consider it as she soars away. Overnight, Ash and his classmates return to the Pokémon Center for a meal prepared by Nurse Joy.