Secret coders

"Dr. One-Zero won't stop until the whole town--no, the whole world--embraces the 'true happiness' found in his poisonous potion, Green Pop. And now that he has the Turtle of Light, he's virtually unstoppable. There's one weapon that can defeat him: another Turtle of Light. Unfortunately, they can only be found in another dimension! To open a portal to this new world, Hopper, Eni, and Josh's coding skills will be put to the test"--Back cover.