When Sam is Bumblebee Boy, he likes to fly alone, using his imagination to battle dragons, pirates, and tigers. Sam's little brother, Owen, would like to play with him, but Owen doesn't have a cape or a mask, and Bumblebee Boy doesn't need his help. But when more aliens than Bumblebee Boy can handle land on the moon, will he be able to defeat them by himself?

Through their imaginary adventures, Sam and Owen discover just how much fun a brother can be, and learn that there are times to play alone and times to play with others.