The JumpStart gang are preparing for a science fair when Casey repeatedly tries to interfere with the projects there. After being told off by Eleanor, Hopsalot arrives with his own project: a hot air balloon.
While the others continue to set up the fair, Casey ends up climbing into the balloon and flying away. Afraid they will miss the fair at 6, the gang is led by Frankie onto a ship. After several hours, the others arrive at a place called Jungle Island.
The gang searches on the island for a while before eventually finding Casey, who says that he has learned his lesson. Hopsalot and the others speed back to the fair, making it just in time. Hopsalot's hot air balloon wins, and Casey helps him with his medal.