A familiar Eevee eats a Nanab Berry, after which a montage of the Where Are You Going, Eevee? segments detail Eevee's journey before it reached Melemele Island's shores. As it emerges from its home under a tree, Eevee spots a Heart Trim Furfrou and tackles it to get its attention, but Furfrou is only agitated. As Eevee attempts to tackle it again, Furfrou dodges and Eevee lands face-first in a pile of sand. The pair's brief encounter ends when Furfrou's Surfer Trainer calls for it to come home. Eevee is instantly reminded of Ash and his classmates' Pokémon and rushes off to find them.
Elsewhere, Lana is woken up by her mother and Harper and Sarah, who announce that their father will be returning home from an expedition in which he catches Pokémon for a laboratory. Lana volunteers to buy some malasadas for dessert, and she goes to the Hau'oli City Mall with Popplio. As she does, she catches Eevee's attention. Unbeknownst to it, Eevee attracts the attention of Pershie as it waits for its Trainer, who is busy trying on jewelry. The Alolan Persian waves Eevee over and appears to be friendly, but as Eevee gets closer, Pershie takes a quick swipe at it. Eevee flees in fear, but Pershie pursues it. As Lana orders her malasadas, Popplio spots the Eevee and rushes off to rescue it from Pershie. Lana soon realizes she is by herself and abandons her order to look for Popplio.
Meanwhile, in the fruit market, Ash and Anela watch as Ash's Pokémon enjoy some Berries. Pikachu spots Lana as she runs by and alerts Ash. Ash quickly learns that Popplio is missing. Elsewhere, Popplio catches up to Eevee, and they seek refuge from Pershie behind a bush. However, it spots Eevee's tail and pounces on them, forcing them to continue fleeing, but Popplio is struggling to keep up its pace on land. In a last-ditch effort, Popplio latches onto Eevee's sides and uses Aqua Jet, slipping Pershie. Then, the two nearly run into the Furfrou from earlier in the day, and though they avoid a collision, Eevee and Popplio fall into a nearby canal in the process. Pershie watches on from a footbridge but retreats after its Trainer calls it back.
Popplio saving Eevee from Team Skull
As the rest of Ash's classmates join Ash and Lana to look for Popplio, Eevee and Popplio wash up on a beach. Eevee spots a Garbodor, Zubat, and Salandit playing nearby and rushes over to them. Popplio quickly realizes the Pokémon belong to Team Skull Grunts Tupp, Zipp, and Rapp, just as Eevee tackles the trio of Pokémon and angers them. Tupp and his cronies arrive, and when Rapp spots Eevee, she hugs it and calls it cute. She demands that they bring it home, but Zipp reminds Rapp that having an Eevee around would only irritate Tupp because of his history with Ilima. However, Tupp comes to the belief that having an Eevee by his side would attract girls to him just like it did for Ilima, prompting him to try and claim Eevee for himself, but Rapp refuses to hand it over to him. Rowlet spots the group as Tupp and Rapp quarrel and alerts Ash. Pikachu arrives and uses Quick Attack to save Eevee from Tupp and Rapp, while Popplio catches it. Lana is overjoyed to see Popplio but is perplexed by Eevee as it greets the group's Pokémon. Ash and his classmates quickly realize that Eevee is apparently friends with their Pokémon already.
Tupp demands Ash and his friends hand over the Eevee to them, but this immediately infuriates Rapp and the pair argue once again. Lana scoops the Eevee in her arms as the trio of Grunts continue to quarrel. Ash is unimpressed by Team Skull's behavior and shouts that they don't deserve Eevee because they do not treat Eevee properly. The claim immediately infuriates Tupp, Zipp and Rapp and the trio decide to take Eevee by force. Ash calls on Pikachu's assistance, but Popplio, wanting to defend its Eevee friend, decides to join the confrontation. The trio of Grunts make the first move, with Salandit launching a Flame Burst, Garbodor attempts a Sludge Bomb and Zubat screams out a Supersonic. Lana calls for Popplio to use Aqua Jet, but the attack instead develops into a powerful wall of water which washes over Team Skull's attacks. Everyone is surprised by the surge of power and Rotom confirms that Popplio has learned a new move, Surf. Lana is even more shocked to see Eevee join Popplio atop the wave and Eevee sends Team Skull blasting off with its Double-Edge. Kiawe and Charizard are startled as the Grunts soar passed them, and the pair soon join Ash and the others. Eevee is left with a large bump on its head from the impact, but is happy to be with its friends. Lana pets both Popplio and Eevee, as the others note that the pair of Pokémon make a great team. Ash suggests that Lana that she should catch Eevee, and the idea startles Lana at first. She watches as Eevee plays with Popplio in the ocean, and seeing its affinity with the sea, she decides to nickname it "Sandy." Her classmates are a little surprised, since a Pokémon is usually supposed to be nicknamed after it's been caught. Lana and Popplio formally ask Eevee to join them, and it happily agrees to the idea. With that, Lana pulls a Dive Ball from her pocket and throws it into the air. The Dive Ball soon pulls Sandy inside, and after a few sways, the capture is complete. Lana performs a victory pose with the Dive Ball in hand.
Back at home, the family feast is all prepared as Harper and Sarah parade around with Sandy. Lana's father arrives home, and the twins happily embrace him. Sandy rushes into Lana's father to greet him, much to his surprise. Lana explains that she only caught Sandy today and that it loves the sea. Lana's father instantly remembers that he recently saw an Eevee out at sea riding on a Mantine. Lana goes on to give Sandy's long fringe a haircut, much to Sandy's pleasure. With the hair now out of its eyes, the family takes a photo to commemorate the occasion.