Ash is ready for his battle against Olivia, but to his astonishment, every time he throws a Poké Ball, it fails to release the Pokémon inside and drops down ineffectively. Wondering what's wrong, Ash picks up one of the Poké Balls, just as it grows and turns into a Voltorb, which then electrocutes Ash. Ash wakes up panting heavily, drenched in cold sweat, and screams so loudly that it wakes his sleeping classmates. Later, at the breakfast table, Ash declares that he can't wait for his upcoming grand trial against Olivia. However, both Professor Kukui and Olivia remind him that he has to clear the island trial first.
Kukui and Olivia inform the students that, as part of their daily curriculum, they will be divided into three teams, provided with maps with some basic information, to fetch all the ingredients that are essential to prepare the island's years-old delicacy: the Akala curry. Kiawe and Lillie are paired, followed by Lana and Sophocles, and lastly, Ash and Mallow. The three items Ash and Mallow are to collect are Mago Berry, Revival Herb and Miracle Seed. Mallow is excited and states that Miracle Seeds are exceedingly rare. As Ash and Mallow begin to leave, Olivia calls Mallow back and shares some secret with her, unbeknownst to Ash.
First, they decide to collect a Mago Berry. According to the map, the tree can be found at a nearby hilltop, which Ash quickly locates. Mallow and Ash venture up the hill, but when Ash wakes the sleeping group of Fomantis, the angry Fomantis attack with a combined Leafage attack, forcing them to retreat. With the group of Fomantis standing guard between themselves and the Mago Berries, Ash decides to send a half-sleepy Rowlet for the job, who can fly silently to the summit and collect the berry. But the plan proves to be ineffectual, when it falls asleep midway. Seeing no other alternative, Ash and Mallow carefully tiptoe to the summit, but unfortunately get struck by a Parasect's Stun Spore on the way. Ash and Pikachu nearly sneeze, but they manage to hold their breath, comically inflating their cheeks. Mallow and Steenee see this and try to hold in their laughter, also getting comically inflated cheeks. The sound starts to anger the Fomantis and seeing this, the group quickly get on their way to the Mago Berry. Just as they reach the summit, Ash trips over and falls flat on his face. As everyone laughs, all the Fomantis become enraged and fire Leafage and Solar Beam collectively at them. Ash is sent flying, and crashing downhill, but fortunately, with the Mago Berry clasped tightly in his hand.
The next ingredient is a Revival Herb, that can be found at a nearby rocky mound. Although this task initially appears difficult, Pikachu quickly locates the Revival Herbs using his acute sense of smell. With a little effort, Mallow and Ash squeeze themselves inside the narrow grotto and collect the herbs.
The final ingredient is the rare Miracle seed. The group venture off into a cave with multiple tunnels branching off at every juncture. At one point, Ash falls into a pit made by Alolan Diglett, who quickly attacks and forces the group out of the tunnel. Ash then finds a whisker of an Alolan Diglett which allows Rockruff to navigate the right way out while avoiding the Alolan Diglett living in the cave.
Once they leave the cave, the group find themselves amidst a paradise of colorful flowers and lush foliage. Ash and Mallow find a hollow tree stump, inside which, a wide variety of berries are stacked. Digging into the pile, Ash finds the Miracle Seed. But their celebration is interrupted when a colossal Pokémon swats them away with Petal Blizzard. Rotom identifies it as Lurantis, the Bloom Sickle Pokémon, but its size tells Ash that it is a Totem Pokémon.
Ash summons Litten, and orders an Ember. The move strikes Lurantis, but it charges up a Solar Blade, and viciously retaliates, sending Litten reeling. When Lurantis charges another Solar Blade, Litten interrupts it with Fire Fang. After another Solar Blade misses, Lurantis calls for an ally, and it turns out to be a Castform, that transforms into its Sunny form after using Sunny Day. The bright sunlight allows Lurantis to use Solar Blade without building up power. Castform further helps by incapacitating Litten with a super-effective Water Gun. Being outmatched and outnumbered, Ash sends out Rowlet. After a heated skirmish, Rowlet's Tackle eventually eliminates Castform from the battle.
With Castform's defeat, the effects of Sunny Day also disappear. Taking advantage of the time taken to unleash Solar Blade, Ash has Litten use Breakneck Blitz, which finally knocks out Lurantis. Mallow revives Castform and Lurantis with some extra leaves of the Revival Herbs, and Ash is awarded a Grassium Z by the Totem Pokémon.
Suddenly, Olivia pops out and congratulates all of them with warm embraces. She reveals that, gathering ingredients for the Akala curry was part of the island trial. Ash suspects Mallow's involvement in Olivia's plan, to which she sheepishly gives a nod. They celebrate Ash's victory, nevertheless.
While relishing the palatable dishes of the Akala curry at the dinner table, Ash is informed by Olivia, that he is now eligible for the grand trial. Olivia adds that she is going to be a formidable challenge. Ash excitingly and enthusiastically contemplates his upcoming hurdle, as the sun sinks below the horizon.