The episode begins once again with the group walking tired through a forest, with Ash wondering where they are and May wanting to get to her first Contest Hall in Kanto. The group are depressed, but Max points out something in the distance which gives them hope and a way out of the forest: A large tower peaking out over the trees. Brock suggests that they go towards the tower, and Ash agrees happily. However, before they can even move an inch, a small Caterpie appears in front of them, screaming loudly. Brock is shocked, and May checks the Bug type Pokemon on her new cream coloured Pokedex. The Caterpie calls for what appears to be its trainer, a small boy with green hair who was hiding in the tree above them. The boy jumps down and orders his Pokemon to use String Shot on what he believes to be 'suspicious characters'. Ash protests their innocence, but the boy is having non of it and orders Caterpie to use String Shot again.

However, a loud booming voice from above snaps all of them, including the boy and his Caterpie, to attention. Looking up, the group sees what appears to be some sort of professor who is flying down towards them with makeshift wings. The man introduces himself as Doctor Gordon and shows off the invention on his head; a small monitor that he believes can show the future. Doctor Gordon rants on to the group for a short while, but there seems to have been some misunderstand that Ash and May manage to explain when the Doctor finally gives them a chance to talk.

The group are finally released, and we cut to what appears to be Doctor Gordon's laboratory.The boy apologises, and says that he was only trying to protect the lab. Ash smiles and says that it's okay and that they wouldn't dream of harming or stealing anything from the lab. The boy introduces himself as Zenkinchi, and the group tell the young boy their names. Max comments that his Caterpie is cool, and the bug Pokemon blushes at his compliment. Zenkinchi explains that Doctor Gordon is his teacher makes amazing inventions. May looks a little unimpressed at this statement, having seen one of the 'amazing' inventions before when they were tied up. Suddenly, Doctor Gordon appears to show off his inventions. At his call, a container rises out of the lab's pool and opens to reveal some of the projects he is working on. The group look on amazed as Gordon explains some of his inventions... a Jigglypuff Karaoke microphone, a Magnemite massaging chair, and various Pokemon mask with special functions. Gordon decides to give them an example and picks up the Jigglypuff mic and sings into it and instantly starts to yawn and falls asleep.

While Zenkinchi tries to wake the Doctor up, Team Rocket watch on from outside the lab. James and Meowth, excited think of the what things lie inside Gordon's lab, but Jessie reminds them what happened the night before... when they tried to break into the lab, a Caterpie appeared and used String Shot on them. James doesn't seem worried however, and tells Jessie that they are prepared this time and Meowth agrees.

Back with the group, we find them outside of Gordon's lab ready to head off. Zenkinchi wishes May luck on her Contests, and May thanks him. Just at that moment however, Caterpie starts to freak out and runs off by itself leaving the group wondering what is up with it. Gordon suggests that they follow, and Zenkinchi agrees and they run off after Caterpie together. Ash says that they should go and help, and they do so, following Gordon and Zenkinchi. Inside the lab. Team Rocket are looting the place, grabbing as much as they can carry. Just as they are about to head off with their booty, Caterpie appears followed by the group. Ash and May shout at Team Rocket, and Gordon asks if Team Rocket are their friends. Zenkinchi tells Caterpie to get ready, and tells his Pokemon to attack the intruders. Jessie sends out Seviper who towers over the small bug Pokemon and stopping it from attacking Team Rocket. Meowth jumps at the window, and tells his comrades to hurry up. James spots an important looking orange briefcase and grabs it, before he and Jessie run off ignoring Gordon's pleas to stop. Zenkinchi tells Caterpie to grab the briefcase with String Shot, and it does so, snatching it out of James' hands. Jessie angrily tells Seviper to get it back, and Seviper grabs the briefcase in its mouth and snaps the String Shot. Ash decides that it's time for him to get into the action, and tells Pikachu to use Quick Attack. Pikachu rushes towards Seviper and smashes into it, sending the briefcase flying. The force of the briefcase smashing into the ground sends it flying open and the contents spilling everywhere. Several small blue balls roll towards Caterpie and Caterpie eats one of them, much to Gordon's dismay. Before their eyes, Caterpie starts to glow and grows larger than everybody in the entire room. Team Rocket, worried at this new development, beg Caterpie not to hurt them. Caterpie shakes its head and tackles them. The force of the attack sends Team Rocket flying out of the window and blasting off.

Zenkinchi walks over to his Caterpie, wondering what has happened to his friend. Gordon explains that it was the effect of the Rare Candy, which cause growth in Pokemon. Zenkinchi begs Gordon to help return his Caterpie to normal, but Gordon isn't worried and says that he will sort the problem out no sweat. Zenkinchi thanks him, but things don't stay peaceful for long as Caterpie starts to glow and grow again, this time breaking through the ceiling of the lab's room. As Caterpie continues to grow, the group run outside as the room begins to shake. Outside of the lab, they see that Caterpie has grown enough for it's head to be seen out of the top of the lab. Zenkinchi shouts for his Pokemon, but Catepie doesn't appear to hear him and crawls down the side of the lab and runs for the nearby tower that the group saw before they were attacked by Zenkinchi and his Caterpie.

The sight of the giant Pokemon sends the nearby town in which the tower is situated into a panic, as alarms sound while Caterpie stampedes through the streets. Doctor Gordon thinks fast however, and puts on his Machoke suit which appears to give him Machoke like power enabling him to pull along a cart with Zenkinchi and the group riding inside. May says that they have to catch up to Caterpie soon, as Zenkinchi begs his Pokemon to stop. Caterpie does however, at the tower in the middle of the town. The group stop and watch, shocked, as Caterpie crawls up the tower. The force of such a large Pokemon causes half of the tower to snap off, and it eventually stops to rest on the new top of the tower. Officer Jenny appears, and asks Gordon if the Caterpie is so big because of one of his experiments, and Gordon admits that it was all his fault. Suddenely. Caterpie begins to glow and the whole group including Officer Jenny look up in amazement as Caterpie evolves into Metapod. May checks the new Pokemon on her Pokedex, and the group wonder what will happen next... one things for sure, as Brock points out, they have to do something. Zenkinchi runs over to the bottom of the tower and begs Metapod to come down, but Metapod doesn't appear to hear him and stays put.

On the other side of town, Team Rocket look on amazed at the transformation that Caterpie has undergone since they last saw it. Meowth says that it's a pity that they didn't get some of that Rare Candy for themselves, as James looks depressed at the floor. Wobbuffet however, holds out its hand to reveal three Rare Candies, which Team Rocket evilly make plans with. Back at the tower, Officer Jenny asks Gordon to do something about the Metapod, but are interruptedby Team Rocket. The three perform their motto. When they finish, Jessie tells Doctor Gordon that they're going to make him a Team Rocket member whether he likes it or not, and will help them with his inventions. Gordon looks puzzled, and Meowth extends a mechanical claw to grab the Doctor. Ash tells Pikachu to use Quick Attack on them, and James responds by sending out Cacnea to use Pin Missile. Pikachu races towards Team Rocket, but one of the missiles hits Pikachu and sends it flying back. Jessie, seeing her chance, throws Dustox all three of the Rare Candy, but only two of them reach Dustox's mouth, with the other falling into Cacnea. The two Pokemon are affected in the same way Caterpie was, and instantly grow large and tower over the group. James tells Cacnea to attack, but Cacnea has other things in mind and turns around to face its trainer, hugging him and crushing him at the same time.

Dustox lowers itself to the ground, and Jessie runs over to her Pokemon dragging Doctor Gordon behind her. Meowth tells James to hurry up. The three jump on Dustox, and Ash tries to catch up to them but fails to do so as Dustox flies off with Team Rocket and Gordon riding on top of it.

Almost like it sensed that Doctor Gordon was in trouble, Metapod instantly starts to glow as Dustox flies away and evolves into Butterfree. Zenkinchi shouts to his newly evolved Pokemon, asking it if it will help him find and rescue Doctor Gordon. Butterfree agrees, and Ash says that he'll go with them.

Flying through the skies is Dustox, while Doctor Gordon is impressed at how big it was able to grow. The three tell the Doctor what is in store for him... he'll help them in their plans with his inventions. They are cut off however, as James notices that Ash, Zenkinchi and his Butterfree are flying after them. Jessie tells Dustox to go faster, and Zenkinchi does the same. However, Jessie then tells Dustox to fly above them and use Poison Sting which Butterfree skillfully dodges. The said cannot be said for Brock, May, Max and Officer Jenny however, who are following them below in a jeep. Ash tells Pikachu to use Thunderbolt, but Dustox also dodges. Ash clenches his teeth in frustration, but seeing some power lines ahead gives him an idea. Telling Pikachu to use Thunderbolt again, but this time on the power lines, he manages Dustox to stop quickly in front of the power lines and try to fly under them. Seeing his chance, Ash tells Zenkinchi to attack, and Zenkinchi orders Butterfree to use Supersonic. Butterfree does so, knocking Dustox and confusing it. Whether the effects of the attack are to blame or not, Dustox instantly shrinks back to its normal size and Team Rocket with Doctor Gordon fall to the ground. Zenkinchi calls out to Doctor Gordon, and Butterfree sweeps in and catches the Doctor saving him from harm and releasing him from his constraints. Team Rocket however, continue to fall and land in a lake.

Crawling out rejected with Dustox circling overhead, Jessie doesn't want to admit defeat says that they can still kidnap Doctor Gordon. However, Officer Jenny along with Brock, May and Max appear. Jessie isn't worried though, and orders Dustox to use Psybeam. Butterfree swoops down behind them, and Ash tells Pikachu to use Thunderbolt, zapping Team Rocket and Dustox. Butterfree finishes them off by using Whirlwind to send them blasting off again.

With all the trouble over, Butterfree turns back to normal and shrinks back to it's regular size. Zenkinchi and Butterfree hug, and May comments that they make a cute couple.

The episode ends with the group smiling and thinking back at the day's events while the sun sets over the shining lake.

Thanks to Alfonso for writing this for us