"Scientist Pablo and his assistant accidentally use a growth formula on a Worman. Now they need Groundskeeper Tyrone's help to stop the clumsy giant creature!"
Uniqua and Pablo are in the backyard wearing goggles. They introduce themselves to the viewer as scientists Uniqua and Pablo. They sing "A Major Breakthrough" as they explain what formulas and potions they have created. They also discuss what potions they are working on.
The backyard transforms into a university's park. Uniqua and Pablo attempt to get to their lab by running across the grass, but Groundskeeper Tyrone stops them and tells them that they have to step away from the grass because his job is to make sure all of the grass in the university is at the same height. They accept and walk around the grass rather than across. They enter the laboratory and begin trying to make a growth formula as they sing "Mix It Up". They succeed in their project and test the potion on some popcorn. The snack food grows larger and larger. The scientists congratulate themselves and leave the lab. The duo's lab Worman, Sherman, squirms out of his tank to eat some popcorn.
Sherman devours the food, causing him to grow. He eats more and more as he continues to increase in size. Sherman giggles as the scientists return to their laboratory. Uniqua and Pablo gasp as they watch Sherman grow and later escape from the lab. Uniqua exits the building and tells Pablo to create a shrink formula. Uniqua alerts Groundskeeper Tyrone about the rapidly growing lab Worman. Tyrone agrees to help Uniqua find Sherman while Pablo makes a shrinking potion. They sing "Where'd It Go?" as they search for Sherman while he hides from them. Pablo rushes outside with a beaker of formula.
Uniqua pours it into her spray bottle and squirts it at Sherman. Sherman's coloring turns from yellow to pink. Uniqua's face reddens as she scolds Pablo for creating a pink formula rather than a shrink formula. Pablo returns to the lab as Tyrone and Uniqua go to the library to find the new pink Worman. Pablo pours various potions in another beaker, hoping that it will turn into a shrink formula. A green liquid appears in the beaker.
Pablo gulps as he fears that another mishap will happen. He runs to the library in search of Uniqua and Tyrone. He finds the two and spills the new formula. He squirts Sherman with the liquid as stinking lines start fuming from his head. Uniqua scolds Pablo once again for creating a stink formula rather than a shrink formula. The characters sing "That Worman Must Shrink" as Sherman continues to grow.
Pablo runs back inside the laboratory. He mixes the last few potions into the last empty beaker. He runs outside, only to hear that Sherman will not listen to Uniqua or Tyrone. Sherman disobeys them when they tell him to stand still.
Pablo then gets an idea. He decides to lure Sherman over with his favorite food, popcorn. Tyrone uses his crane machine to drop giant popcorn kernels on the ground. Sherman catches a whiff of the delicious food and squirms over. He eats the popcorn as Uniqua sprays him with the final formula. Sherman changes from stinky, pink, and huge from pleasant-smelling, yellow, and small. Uniqua, Pablo, and Tyrone all give huge sighs of relief.
Uniqua's stomach rumbles. Pablo asks her if the sound is another giant Worman, but Uniqua assures him that it is just her stomach. Pablo invites the two over for more popcorn. The others accept as the college transforms back into the backyard. The children sing the end song and enter Pablo's blue house. Pablo and Uniqua open the previously closed door and exclaim, "I made a shrink formula!"