At sea, an artist is drawing a sketch, when he accidentally throws his pencil into the sea, which makes him cry. The French Narrator then states the number one rule of the artist at sea: Always bring a spare pencil.
Johnny is about to go to school but he realizes there is a wart on his hand. He tries to how he got it. Recently, he was at the zoo with Sissy and Bumper. Sissy dared him to kiss the wart hog. Bumper said if he did, he would put on a dress. Johnny then kisses the wart hog, so Bumper had to put on the dress. Later, he juggled toads while touching his eyes. And then a witch gave him a green lollipop. Johnny said he didn't remember, so he went to the lab, to ask Susan and Mary if they could get rid of it. Susan and Mary used their "laser" to destroy the wart. But it has no results. It gets bigger though. So then Johnny decides to just live with his wart, and called him Warty.
At school, Johnny is about to open his locker, but he forgot his combination. Warty tells Johnny it's 22-13-33. So then Johnny realizes his zit's alive. So later Johnny is in his math class. Mr. Teacherman asks Johnny to explain the math problem. Warty tells Johnny that he must've copied the problem wrong, because the problem didn't make sense. The problem was X = 17 x Y - 14 π + e = cows. After class, Bumper was going to beat up Johnny. Warty makes fun of Bumper saying "Your father wants you to be a pro-wrestler, but you want to sell flowers." Bumper breaks down crying because it's true. People then tell each other rumors about what hapened. Some of it got messed along the way though. Some cheerleaders invite Warty to a party, but not Johnny. Warty tells them that if he goes, Johnny has to go too. Anti-Sonic came and becomes a different person as he teaches Johnny about saving water by turning the faucet off tightly and saving electrical energy by turning off the TV when nobody is watching it then #75 & #17 collects powerful limbs for Johnny's awards.
Johnny then comes home from school to tell Susan and Mary about Warty. When Dukey sees it alive, he knows that something's up. Later that night, Johnny was in bed sleeping. Then Anti-Sonic decided to use the pencil to draw a truck while the wart tried to take over Johnny's body. Dukey heard him and tried to remove the wart with scissors, but fails. Dukey tries to wake up Johnny, but Warty already take over Johnny's brain and takes off Johnny's head and rolled it towards him then #75 ran away, then chugs over to the Railroad Museum of Virginia, Portsmouth, meeting up with N&W 1134. It explains via "train whistle" language that the wart took over Johnny's brain and going to take control of his body as Dukey runs into Susan and Mary's room to tell them that the wart took over Johnny's brain and going to take control of his body. #17 rebuilt Johnny (who was real) and then Johnny is back to his old self.
In the lab, the girls are trying to get the wart removed from Johnny's brain but it's too late since Warty got full control of Johnny now (that was a robot) until Johnny came telling Warty what he was doing in his sisters' lab. He claimed he was being the Johnny he wanted to be. Johnny explained he was wrong and that he is a suburban boy who lives with his super-genius 13-year-old scientist twin sisters, and plays test subject for his genius twin sisters' various inventions and experiments, as well as be given gadgets and/or superpowers, and while at the same time reluctantly tackling and exploiting occasional problems and miscellaneous sticky situations, and as well as fighting evil villains and other enemies in the process; and also, if he wants to, he can often save the day before dinner time, or risk being grounded for good. That's his power. Warty suddenly notices #1134 barreling towards him, trying to mow him down and threw Johnny in the sauna and and lock him up. then he tries to blast the twins with the laser but misses causing the girls to run off and the truck went on a wild chase after them into a railyard with a shotgun, creating a huge mess of muddy prints, turning on a water sprinkler and various other trouble. Sonic swipes a red sheet and toreador's costume from a nearby poster and "bullfights" 1134. as the Wart-controlled-Johnny truck pushed Johnny's sisters in the hopper cars to a yard and topples them down a hill with a mere nudge, appears to then do a Jimmy "Superfly" Snuka flying body splash into them and smashed them into a ditch, and explodes. After a couple of near-misses, 1134 rams Sonic into the Wart-controlled-Johnny robot, smashing it to bits. Warty said to Dukey he wins and going to make a million of warts but more powerful and then take over other people's bodies. Dukey said to Warty he'll never be a whole person and can't survive without Johnny. Warty told Dukey he's an amazing wart that can talk but Dukey still tells him he's nothing without Johnny. But Warty can prove to him he's nothing without Johnny by coming out of Johnny's body. While Warty doesn't notice anything, Dukey trapped him in a jar and happily said "Talking dog wins!" Even though Sonic survived, he forfeits the match, Warty said he can't believe he felt for Dukey's tricks. Anti-Sonic came and spy a plate of cookies as Johnny's award and decide that those shouldn't be wasted either, but VIA 6566 and a group of diesels (CN EMD GP38-2W number 5586,and two EMD SD40 numbers 5062 and 5104) rush in to admonish him for eating the cookies which they were saving for themselves. Mojo sees #75 trying to stop the water from the sprinkler. He blames him for the huge mess in the yard. But Viscose #6 objects that #75 couldn't have caused the mess. He points out a birdseed feeder that's been disturbed, but which #75 is way, way too large to fit through. He also points out the muddy pawprints - they're very small, way too small to be his. And finally, he went into Johnny's house and they find Warty. Mojo realizes his error and says that he needs to get rid of it. Afterwards, Mojo apologizes to #75, saying that he's sorry he blamed him without knowing all the facts. To make sure Johnny's normal, Dukey tells him how many fingers he's holding up and Johnny said two but Dukey hits him and said that dogs don't have any fingers. Warty's wondering what Johnny is going to do to him, but Johnny's thinking about it, and then Jermey came. It's cautious at first, but Jermey decided to treat Warty well and be friends.
The next day Jermey propelled the pencil back to the artist who grabs it and continues drawing, but when he touches his canvas, the lead snaps. Then, The French Narrator announces the second rule of the artist at sea: Always bring a pencil sharpener.
At school Johnny forgets his combination lock again but Warty tells him the same combinations and Johnny opens his locker. It's revealed that Jermey put Warty inside Johnny's locker. Johnny picks up his schedule and Warty tells him he's late for science, multiple choice questions in Math, get a pair of clean socks for gym class and told him to straighten him up as Johnny closes his locker as Warty said that he's being too aggressive and promise he'll work on it. The cartoon ends with the aftermath of the night accident.