Ash and his friends find a tree full of delicious honey, the scent of which has attracted several Pokémon, including Ash's Aipom and a wild Burmy. The Burmy has also attracted the attention of a Trainer, Cheryl, who captures it with her Chansey. Cheryl is a treasure hunter in search of the Enchanted Honey that's said to lie within the Amber Castle. But to find it, she needs a male Burmy she can evolve into Mothim, which has an amazing sense of smell.
Ash offers to help evolve Burmy by letting it battle Turtwig. It should be easy for Burmy to beat a Grass-type, but this Burmy isn't very robust! It loses the match and gets seized by Team Rocket as part of a nefarious plot to evolve it into Mothim and impress Giovanni. After Team Rocket makes their getaway with Burmy, however, they discover that Burmy's better at eating all their food than it is at battling.
Just in time, Cheryl and our heroes arrive to rescue Burmy. Burmy manages to help rescue itself by teaming up with Chansey to defeat Meowth and Wobbuffet, and it finally evolves into Mothim! The stage is set for everyone to join forces and send Team Rocket blasting off. That's not all—Mothim then picks up a scent and leads Ash and the gang towards a new chapter in the search for the Amber Castle!
Ash and his friends pursue Aipom as she swings through the trees to get some honey. A Burmy soon arrives, equally captivated by the honey's scent. After Burmy falls out of the tree, Cheryl and her Chansey step out from the bushes, determined to capture the Bagworm Pokémon. Chansey's Attract works on Burmy, much to Cheryl's excitement. Ash and Dawn comment that you have to attack a Pokémon to make sure you catch it, so Cheryl orders Double Slap which hits its mark. Burmy replies with a Tackle, though Chansey tries another Double Slap. This time Burmy uses Protect, so Chansey follows up with Egg Bomb. Cheryl promptly throws her Poké Ball and catches the Burmy.
Afterwards, Cheryl formally introduces herself as a treasure hunter, who is inspired by her grandfather's adventures. Brock steps forward to confess his love to Cheryl, though Croagunk pulls him away. Over some tea, Cheryl says she is hoping to locate the Enchanted Honey, said to be sweeter than any other honey. Cheryl pulls a map out from her bag, and explains that deep within Eterna Forest is a secret place called the Amber Castle, known to have Enchanted Honey. She calls out her newly-caught Burmy, and asks for it to evolve into a Mothim, hoping its sense of smell will guide her directly to the Amber Castle. Dawn wonders why she hasn't just caught a Mothim instead, though Cheryl explains that only male Burmy evolve into Mothim. She goes onto show them her three Wormadam, adding that they were all female Burmy before they evolved.
Ash decides to give Cheryl a helping hand and calls out his Turtwig to battle Burmy. Cheryl starts off with a Tackle, but Burmy simply bounces off Turtwig. Turtwig replies with its own Tackle, but the attack is too powerful and knocks Burmy to the ground. Burmy gets to its feet, but trips as it tries to use Tackle again. Its leafy cloak falls off, and two leaves cover Turtwig's eyes. Turtwig panics, and it accidentally Tackles Burmy, who loses. Dawn says that Turtwig is being a little rough, so Ash swaps it out for Pikachu. Pikachu uses a small Thunderbolt, which Burmy takes weakly. Cheryl tells Burmy not to give up, and use Tackle. Pikachu doesn't dodge it, and pretends to be damaged severely.
Burmy rushes forward to attack again, but Team Rocket snatches it with their extendable hand. They fly off with Burmy, to try to get him to evolve and get the Enchanted Honey for themselves. Ash orders a Thunderbolt from Pikachu, though Jessie has her Seviper use Haze to make a clean getaway. So Ash calls out Staravia to search for Burmy. Meanwhile, Team Rocket get straight into some special training, and order Wobbuffet to be Burmy's first opponent. Meowth, however, translates that Burmy is too hungry to battle, so the trio spoil him with a meal first. Jessie and James aren't too thrilled after Burmy eats all of their supplies, but remind themselves that the Enchanted Honey is their true prize. They start the training, though Wobbuffet uses Detect to block Burmy's oncoming Tackle, much to Jessie's frustration. Meowth goes next, but ends up knocking Burmy out with his Fury Swipes. Jessie decides a pep talk is in order, however her blunt message only frightens Burmy.
Before long, Staravia has zeroes in on Team Rocket's location, leading Cheryl and the others directly to the evil trio. Cheryl pleads with Team Rocket for her Burmy's return, but Jessie and James are determined to settle things with a battle. Seviper and Carnivine are sent out, so Dawn orders Piplup use Bubble Beam. Pikachu follows up with Thunderbolt, though Team Rocket’s Pokémon move out the way in time. With the battle raging on, Brock and Cheryl rush over to collect Burmy, though Meowth and his sharp claws are waiting. Cheryl calls on Chansey, taking care of Meowth with a Double Slap. After taking care of Wobbuffet, Burmy makes its break for freedom, bowling Meowth over in the process. Meowth to retaliate with Fury Swipes, but he and Wobbuffet are struck down by Burmy's Hidden Power. Burmy then evolves into a Mothim. Cheryl has Chansey and Mothim use Egg Bomb and Psybeam to knock Seviper and Carnivine out. With Team Rocket now in a heap, Ash has Pikachu use Volt Tackle to send Team Rocket blasting off. Afterwards, Mothim picks up a scent, so Ash, Cheryl and the others follow after it in the hopes of discovering the Enchanted Honey.