One day, two kids named Scott and Laurie and their basset hound Barney are magically transported into a coloring book! This coloring book is a mystical, magical land called "Sillyville." While there, the kids meet up with Sillywhim, a happy, sing-songy lady who tells them of Sillyville's troubles. The Yellow Spurdurgurgles, Blue Twirlypops, Green Jingleheimers, and Red Bittybooties are all fighting because they do not wear the same colors! Scott, Laurie, and Sillywhim meet up with all of these coloful characters, plus a talking tree, a singing acorn, and the kindly purple-wearing Pasha who all sing songs about themselves. Will the kids and Sillywhim be able to reunite all of the people of Sillyville? You can bet your magic rainbow blower on it!

Wee Sing characters Punchinello, Sillywhim, Little Bunny Foo Foo, Weeber, Snoodle and Doodle, and Trunky (originally Tusky) who are all from earlier Wee Sing Videos, ride the Wee Sing Train to Singalingaland where Singaling (voiced by Mikey Moran) and Warbly (voiced by Maureen Robinson) are hosting a big musical party called "The Wee Sing Festival". Singalingaland also happens to be an extension of Tim and Annie’s game board, Wee Singdom. However, the main guest of honor (a singing rainbow) is missing, so as each character performs his or her respective performance, Chug-a-Long the engine and Cubby the caboose are sent to go look for her by asking a cirrus, stratus, cumulus cloud where she disappeared too. Eventually, she is found after Tim and Annie find her playing with their cat friend, Staccato, and as a reward, Chug-a-long and Cubby invited Annie and Tim and Staccato to attend the Wee Sing Festival, and Singing Rainbow is able to perform.