A year after the Tanager kids narrowly escaped from Devil's Canyon, it's time to go back. Their parents have returned to the laboratory where The Little Sun was born to try and put an end to the electricity-killing ball of energy, but they haven't come back.And what's worse, nobody's doing anything about it! So, Sophie, Jack, and Ella Tanager take it upon themselves to travel into the desert to find out what's happened to their parents. Joseph and Rufus are there with them, and they make some new friends too--including a mysterious little bald girl who has lost her memory but gained something else.But they'd better hurry, because something has escaped from The Little Sun, and it has big plans.And they're not good ones.