Nani's middle school friends, Ellen and Lona, return to Kauai for a visit and, thinking that Nani is vice president of the business she works for (which is clearly not true), invite her and her ʻohana on a yacht cruise. Meanwhile, Stitch encounters an experiment that reverts individuals to a primitive state. Lilo, Jumba, Pleakley, Ellen and Lona are transformed into cave people, which causes trouble on the yacht. Now, Stitch must find and capture Retro before it's too late.