In the previous Book 5 of Ukiee the Ukulele is about Koa and his friends trying to put strings on Ukiee the ukulele, but the strings kept popping off. They eventually seek help from Mr. Eli and learn that the ukulele can play without strings. Koa shares the love story of the magical Koa tree and the TV he found on Plastic Island. Koa wants to learn how to play the ukulele.As Koa starts learning how to play the ukulele, he discovers a hidden message...