The Bubble Guppies compete in a Grand Prix-like race to win a big box of crayons. But when Gil, the purple racer goes too fast and crashes, it's up to Molly, the blue racer, and Deema, the red racer to make purple, go through the purple hoop, and win the race!
The episode begins as Molly tries to say "It's time for Bubble Guppies!" However, she notices Gil nearby and swims over to see him playing with a fish that spits out colored bubbles. Eventually, after Gil requests a really big one, it ends up exploding on him! They then both say, "It's time for Bubble Guppies!" Molly and Deema are on the way to school when they go to investigate a noise that
they just heard. They see a blue colored race car just reaching the finish line and a red car is called up. Just beforehand, the girls meet the red racer and chat, Molly and Deema both tell the audience they're favorite colors, blue and red.
Shortly after, the two girls then continue going to school while pretending to drive cars. Upon arrival to class, Molly and Deema tell the others about the race cars and soon everyone shares to the audience what they're favorite color is. Mr. Grouper also points out that you can mix most colors to make a new one by taking the three prime/focal colors: red, blue, and yellow. Then mixing them.
For example, yellow and blue make green, red and yellow make orange, and red and blue can make purple! Then the Guppies sing A Color Just Right.
Oona goes to get her helmet painted at Gil's Shop. She asks for pink. After he looks around however, she suspiciously questions this and can tell he doesn't have any pink paint on hand. But she tells him that they can just make some pink paint and asks for both some red paint, and white paint.
Oona then asks the audience if pink is lighter, or darker then red. Then, after the Little Fist give the correct answer, she dumps some white paint into the red paint can and asks for a mixing stick and begins to stir the two colors to make pink!
Placing both the paint, and helmet into the device that paints objects, Gil turns it on and within a few seconds the helmet is now a pretty soft shade of pink! He then places it onto Oona's head as Mr. Grouper comes to tell them it is now Lunchtime.
Molly begins to explain that pink is a lighter shade of red as she paints the background that very same color. Gil is in his purple racing attire pretending to be a racer as she keeps warning him to be careful due to dangerously getting close to the paint can, which is on top of the ladder she's using. Eventually he bumps into the ladder, causing the pink paint to spill all over him!
In class, Molly and Deema once again pretend to be driving cars and decide they want to have a race around the classroom. Mr. Grouper offers to be the traffic light but he keeps mixing colors or getting the wrong one, so Molly and Deema laughed. To which leads them to discuss what some colors mean. Such as red on an oven meaning hot, so don't touch. Or that blue usually means cold, when using water. Then Goby Sings: What Colors Mean Outside to play, Nonny and Deema pretend to be color technicians that work at a color plant.
Bringing many colors to the world. Suddenly, the orange pipe springs a leak, but Deema fixes it quickly. Shortly after, however, a color monster appears and begins to drink up the blue colors from the blue pipe! He claims it to be his favorite color, then walks away before Deema fixes it. A couple of minutes later he comes back and claims that another color is his favorite, to which Deema questions. Which results in him breaking all of the color pipes and drinking their colors!
Deema hurriedly fixes all of the pipes trying to correct them upon noticing now all of the colors draining from everything. When the monster shows up, she has finally had enough and tells him in an angry voice to stop since he's taking away all of the worlds colors. This makes him sad, since he likes all of the colors of the rainbow and likes to drink them. Deema is then inspired and she tells Nonny to turn on the emergency rainbow generator.
The monster heads to an island where the rainbow ends, so that he can drink as much as he wants and leave the color pipes alone and not steal anymore colors from other items. The monster never bothered the color plant again and they all lived happily ever after.
Gil is holding a race for a group of multicolored little fish and he tells them to start their engines, and then he tells them to go! But they do not move... Molly asks the audience about this, and they inform Gil that the light is still red! So Gil get's in front of it and he begins to play with the light until it suddenly changes!
This causes the many small fish to then nearly run him over and Gil quickly swims away before they do. Deema then approaches and tells them it's time to go to an actual race. They begin after Mr. Grouper warns them to buckle their seat belts first.
Mr. Grouper takes the guppies to compete in the Grand Crayon Prix for a chance to win a big box of crayons! Each Guppy is given a color and they soon begin. Everyone manages to complete their stunt and get back into the pathway along with the others but Gil goes too fast and accidentally crashes and misses his stunt!
So Molly and Deema realize that they can mix their colors and form Purple and they then complete the final stunt! This wins the Guppies the big box of crayons as the episode comes to an end.
Gil comments on how happy he was to see purple. Then goes on to say how awesome it is as the color blowing fish approaches him from behind and begins to blow a huge purple bubble! Molly tries to warn him and swims back to avoid the oncoming purple explosion but Gil tells her to cheer with him. She doesn't, however, and the purple bubble bursts! Splashing purple all over the screen, and Gil as the episode ends.