Ash and friends finally arrive in Petalburg City. Ash heads to the Pokémon Center (PC) to take care of his team while everyone else visits May and Max's house. At the PC, Ash sees Norman talking to Nurse Joy.
At the house, Norman's wife Caroline makes everyone lunch, and she seems very upset. The kids check out the greenhouse where Norman keeps his Pokémon, and his assistant Kenny explains that Norman has been going to the PC everyday to see Nurse Joy. The kids rush to the PC to yell at their father, just as Ash arrives at the house. Caroline shows up at the PC with her luggage and tells Norman she's leaving.
Back at the greenhouse, Ash checks out Norman's Pokémon and gets into a battle with Team Rocket. Everyone returns to the house in the middle of the battle, and something in the greenhouse is damaged that makes Norman very upset. He has his Slaking use Focus Punch on Team Rocket to send them blasting off.
It turns out that Nurse Joy was actually helping Norman prepare a fireworks display for his wedding anniversary, but it was ruined during the battle. Nurse Joys repairs the display, and that night they all watch the fireworks together.
The group has finally returned to Petalburg City, where May and Max are looking forward to seeing their parents, and Ash is after another Gym battle. As they walk through downtown, they spot yet another poster of Norman, and realize he must be pretty famous and idolized here as well. Max and May already knew this, of course, and that he's been undefeated for a while. However, Ash is confident in his team. While Ash splits up and goes to heal at the Pokémon Center, Max and May visit home with Brock. When they get there, Norman's apprentice Kenny greets them at the doorstep, but he quickly changes to a suspicious tone when the children ask about their father. Max and May are left utterly confused, but before they can say anything, Caroline, their mother comes and greets them. She too is acting suspicious and invites everyone inside to enjoy some lunch.
Ash and Pikachu have arrived at the Pokémon Center, and Ash is surprised to see that aside from Nurse Joy being there, Norman is leaning over the front desk engaged in a deep conversation with her. Ash, however, is only psyched about having the Gym battle and proving that he's gotten stronger. Norman is quick to say farewell to Nurse Joy, but the chuckle filled goddbye only leaves Ash curious as to what they're hiding.
Meanwhile, Meowth has dragged his teammates to the Petalburg Gym's greenhouse, trying to devise a new plan. Meowth explains that the twerps are going to the Gym for a battle, and perhaps they can use the old hide-underground-and-snag trick. Back at their lodge, Max and May are eating and bragging about their journeys, and adventures with Team Rocket. Then they tell them about Ash and he's here to challenge dad once again, but once again, Caroline stops dead in her cooking at that mention. Kenny then quickly walks in and steers them off that subject by asking about their adventures. May mentions that her best Pokémon now is Beautifly, but this only infuriates Caroline more. Kenny quickly steps in, through Max mentions that Beautifly helped May to win some Contests. Caroline is now nearly losing her temper, though she turns around and pretends that nothing is amiss. Soon after, Kenny takes Max, May, and Brock into the greenhouse to explain the situation. He begins to warn them that this may give them a nasty shock, but before he gets to it, Max jumps in excitement. They turn around, and notice their old friend Vigoroth hanging from a branch, and Max quickly hugs it. Kenny is again interrupted, this time by the arrival of a Slakoth, and May quickly checks it out on her Pokédex. Max then notices a Slaking resting nearby, so May grabs some info from the Pokédex again. Now, Kenny is getting sick of waiting, so he asks them to kindly listen to him.
As they crowd around, he whispers that rumor has it that Norman has been visiting the Pokémon Center a lot recently and is in love with the local Nurse Joy. Max refutes Kenny’s claims, adding that a lot of people visit the Pokémon Center and yell. Kenny adds that Caroline has been frustrated with the situation, and the mention of “Beautifly” really angers her. Inside the house, Caroline is busy packing her possessions and places a photograph of her and Norman surrounded by Beautifly facedown. Ash suddenly arrives at the greenhouse, interrupting the secret conversation. Team Rocket suddenly notices the twerps, but Meowth declares that Slakoth, Vigoroth, and Slaking would make better presents for the Boss. Vigoroth to wake him up, and Slakoth and Slaking to help him relax after a long day's work. Jessie and James love that idea and decide to go through with it.
Ash informs the others that he saw Norman at the Center talking to Nurse Joy, though the information only alarms everyone. Brock is determined to solve this, calling himself the original "love doctor" as he leads everyone to the local Center. Ash, meanwhile, decides to remain behind after seeing Norman’s Vigoroth. May and the others enter the lobby and they’re all shocked to see Norman speaking with Nurse Joy. Norman notices everyone and happily greets them. May and Max are unable to speak to their father, while Brock pipes up and suggests they have a talk. Brock, however, gets side-tracked by the sight of Nurse Joy, though Kenny pulls him away. He returns to confronting Norman, adding that Caroline is worried sick at home about him, and how Joy is meant to be with him instead of Norman. Kenny then gets extremely aggravated, and pulls Brock away again, dragging him out. Even May is stunned at Brock pulling something like that. Suddenly, a very angry Caroline, with her suitcase in hand, arrives at the Center and reveals she is leaving. Norman doesn't explain still, and Caroline repeats that she is going somewhere else. Norman, however, remains dense. Kenny eventually explains the rumored situation to Norman and Nurse Joy, and the tale takes the pair aback. Caroline reiterates that she cannot forgive him for being unfaithful, especially on the day of their wedding anniversary. May and Kenny urge Caroline and Norman to figure things out, but Max demands that they give Norman the benefit of the doubt. Caroline understands Max's idolization for his father, but is still set on leaving. Though Norman smirks, before explaining that there has been a big misunderstanding. He calls for everyone to head back home where they can figure things out.
Meanwhile, Team Rocket put their plan to steal Norman's Pokemon into motion as they take on Ash with Seviper and Cacnea. Seviper lashes Pikachu with a Poison Tail, while Cacnea attacks Slakoth with Pin Missile. While they all run with Ash, except Slaking who's still asleep, Seviper fires another Poison Tail, breaking the door to the place down and knocking them all out. Suddenly, to his luck, Norman, Joy, Caroline, Kenny and his friends arrive on the scene. Norman is particularly unhappy to see Team Rocket again. He leaps out of the way to evade a Poison Tail and Pin Missile, but the attacks instead strike Norman's surprise fireworks. With rage, Norman yells in a booming voice for Slaking to wake up. Slaking then charges at them angrily, and fires a Focus Punch, blasting them into oblivion.
Norman is still angry that his anniversary present for Caroline has been destroyed. The gesture surprises everyone, and Nurse Joy adds that she can have another fireworks display ready by tonight. Norman gladly thanks Joy, and as agreed Joy finishes fixing it, they set off the machine, and Beautifly-shaped fireworks are shot into the air. Joy also apologizes about being secretive, but she reveals that Norman knew that she is also a fireworks technician. He wanted to arrange a special gift for Caroline to celebrate their anniversary, with the Beautifly fireworks commemorating that day in the flower field with all the Beautifly. Caroline apologizes to her husband for her suspicions, and wishes him a happy anniversary as they hug. While Norman goes in to get some more drinks, Caroline remembers their special day. When Norman returns, he informs Ash that he will use Slakoth, Vigoroth, and Slaking in their match tomorrow. Max, however, still insists that Ash doesn't stand a chance, but Ash is confident. Though May seems to have mixed feelings about who will win, and who to cheer on.