While on Mandarin Island, Ash and co meet a young girl named Emily and a young boy named Ralph. Both trainers are looking for their Nidoran (Tony and Maria). However, the two trainers hate each other because for a long time they have always had the same Pokémon. What's worse is that they're next door neighbors. Things are complicated when Ralph's Tony (Nidoran Male) and Emily's Maria (Nidoran Female) are in love with each other. (Like in Romeo and Juliet), but the trainers don't want them to see each other. Things get even worse than that when Team Rocket meddles. Can Ralph and Emily set aside their differences and help their Pokémon, or will this love story end in tragedy?
The heroes come to a quiet town, thinking it is from a history book or from England. Ash wonders if there were any Pokémon Centers in the old days. Suddenly, a girl runs, shouting for Maria. The girl asks for them if they saw Maria. She sees they are strangers and tells her Nidoran is missing - a blue one. Ash uses his Pokédex, but Maria sees it is a male, as it shows a pink Nidoran. Ash presses some buttons and a blue Nidoran appears, which Maria acknowledges it as female. So, the heroes promise to get Nidoran back to her. They shout Nidoran's name, Maria. Suddenly, Pikachu sees some nice berries and comes closer to the tree, but still "shouts" Maria's name.
As Ash looks, he hears a boy looking for Tony. The boy asks them if they saw Tony, his pink Nidoran, whom he describes nearly same as Maria. Ash looks to his Pokédex and sees a Nidoran. The boy denies this one's appearance, as it is blue, so Ash presses buttons and a pink Nidoran is shown. As Tracey and the girl show up, the boy gets in an fight with her, calling her a kidnapper. The boy and the girl argue with each other, telling each other they stole the Pokémon so that they can have their Nidoran remark as the best one seen. They grab sticks and attack each other. Suddenly, Marill appears and the boy and the girl run over Tracey, finding their Nidoran cuddling each other.
Misty and Tracey see this is love. The male Nidoran offers a rose and they eat the petals, then push their noses as to who will get the last petal. While the boy and the girl like this, they part ways, getting their Nidoran and going away. In a restaurant, the heroes talk with a chef about this problem. The chef knows they are Ralph and Emily, who have known each other since childhood. However, they catch always the same Pokémon and get tied in contests. When they got the Nidoran, the Nidoran fell in love with each other, but due to their trainers' stubbornness, they don't see each other often. As they get out, the heroes see Tony, Ralph's Nidoran. They spy and see Tony wanting to see Maria. Misty sees they are meant for each other. Ash asks how does she know. Misty replies she is a romantic and tells Ash he needs to grow up to understand these things, making him depressed.
Emily appears and throws water out of the bucket, making Tony wet and takes Maria inside. Ralph appears and takes Tony inside his house. The gang notices Ralph and Emily are neighbors. Tracey sees the statement "you can live near someone and be worlds apart". Misty sees this is crazy and goes to unite the Nidoran together. Ash tells her this is not her business to get involved in. Misty replies she will, as she is a romantic and love is the most important thing in the world. Ash replies catching Pokémon is, causing him to get more depressed as Misty called him a baby. Team Rocket see the two Nidorans and Meowth and James think they are set, like Christmas socks. Misty wrote a letter and has a plan to get Ralph, Emily and their Nidoran together (scolding Ash for not seeing how it would work). She thinks she can send them identical letters, thinking they will thank her for this, as they may be not mature to admit they are in love. Tracey compares Ralph and Emily to them, causing him to be outyelled for this ridiculous statement.
Jessie believes they can teach the Nidoran a lesson they can be together if they are with Team Rocket. James thinks Jessie had love trauma. Jessie admits she was looking a long time for love, but found only heartaches, making her sad, as if bad guys seem undeserving of love. Meowth thinks this is what caused her to be a nutjob, causing Jessie to kick them off and order them to make the plan. Meowth contacts Tony and Maria, promising them to see their love if they do what he tells them. Jessie tells James when they got the Nidoran, they will take them to the boss. Meowth appears and tells that they will not disobey their masters, making Jessie mad. Jessie sees there must be another plan - Nidoranapping. The heroes are hiding and awaiting Misty's plan to be realized, thinking Ralph and Emily will thank each other for sending gifts (which Misty did). They appear, but rudely tell why they'd send the gifts, throwing the flowers and airplane in their faces. Ralph and Emily argue even more and fight each other.
Misty sees she was wrong about them liking each other. Ash tells her plan failed, but Misty replies her mission was to get them together, which she did. Suddenly, they see a bride and a groom, congratulating them. The bride and the groom take the Nidoran (which are in the cages). The bride and the groom are Jessie and James, who release a cake, cut it and then fly off in the balloon. Ralph and Emily say their Nidoran's names in sadness. Out of anger and annoyance, Misty snaps at them, saying that what happened was their own fault, and that they have no one to blame but themselves — which eventually causes Ralph and Emily to realize that she is right.
The heroes notice cans were dropping from Team Rocket's balloon and follow the trail. When they get to their place, they demand the Nidoran back (as Jessie and James try to dress them up for the boss). The Nidoran return to their masters, but Jessie sends Arbok. The Nidoran tackle Arbok away, defeating it. James sends Victreebel, who bites Jessie. Maria scratches Victreebel, while Tony gets hit by Arbok's tackle attack. They evade Victreebel's gnawing and Tony tackles it, while Maria scratches Arbok.
Tony gets hit by Victreebel, so Maria pushes it away. Ralph and Emily see the battle and their Nidoran's desire to battle for each other. Arbok wraps the Nidoran, but gets chewed. Ralph and Emily order Fury Swipes, blushing at each other, as the Nidoran scratch Arbok and Victreebel. With a Double Kick, Victreebel and Arbok are defeated. Team Rocket go up and Meowth uses a vacuum cleaner, but Pikachu goes to it (with an evil grin) and electrocutes Team Rocket. Misty sends Staryu, who pierces their balloon. With that, Team Rocket blasts off. Misty tells Team Rocket this is what happens to anyone who messes with Pokémon in love, before she turns to Ralph and Emily and says they are much better than Team Rocket, but they should leave their Nidoran happy. Ralph and Emily realize that they cannot make their Nidoran part ways with each other, but they don't want to release them .Tracey points out can build a house between their own in order to spend time with them.
Misty says to Nidoran that they can finally be together. The Nidoran kiss each other... and evolve into a Nidorino and a Nidorina. Tracey wonders if they evolved from the battle or the kiss, causing Misty to pound him. Ash asks her if a kiss changes people, but Misty replies they should see for themselves — which causes Ash to be confused.
Meanwhile, Team Rocket are tied to the bells, which swing for a couple's marriage.
“If you two weren’t arguing, this wouldn’t have happened! You only have yourselves to blame!” - Misty, scolding Ralph and Emily (who realize that she is right)
“Bet you didn’t expect to see us.” - Ash
“Now give back their Nidoran this second!” - Misty
"It’s the twerps!” - Meowth
“How’d you find us?” - Jessie
“You wouldn’t have been so easy to follow if you had cleaned up your act.” - Tracey, while showing Jessie, James and Meowth the bag of cans that fell off their balloon
“We must’ve dropped the cans!” - Meowth
“I guess I should have tied them a little tighter, huh?” - James to Meowth in a whisper
“I guess I should have dropped you off the balloon instead, huh?” - Jessie
“And so, thanks to our heroes, a near tragedy has a happy ending. It seems the Nidoran and their trainers will live happily ever after, and all’s well that ends well.” - Narrator
(Team Rocket is trapped in ringing church bells)
“Did he say ‘All’s well that ends well’?” - Jessie
“I think so.” - James
“That has a familiar ‘ring’.” - Meowth
“You think people change when they get kissed?” - Ash
"I guess we’ll have to find out for ourselves." - Misty
- Tony and Maria were named after the two characters from West Side Story that fell in love with each other.
- This is the 100th episode of the series.
- Team Rocket broke the fourth wall at the end of this episode.
- The "Who's that Pokémon?" in this episode is Venonat.
- This episode is a reference to Shakespeare's Romeo and Juliet.
- Dexter gets its Nidoran entries wrong by mixing up the genders when Ash first meets Ralph and Emily, despite their trainers referring to their Pokémon as "he" and "she" respectively.
- When Arbok and Victreebel are sent back to their Poké Balls Arbok goes into Victreebel's and Victreebel goes into Arbok's.
- In the scene where Jessie and James go over their plan, Jessie's earring is miscoloured green.
- The narrator says that Ash has had a big victory over Pokémon master Lorelei or Prima, although he hadn't won at all.