Dr. One-Zero has added a new class to Stately Academy's curriculum. But in Advanced Chemistry, they only teach one lesson: how to make Green Pop! While their classmates are manufacturing this dangerous soda, the Coders uncover a clue that may lead them to Hopper's missing dad. Is it time to use Professor Bee's most powerful weapon: the Turtle of Light? From graphic novel superstar (and former computer-programming teacher) Gene Luen Yang, comes Robots & Repeats, the fourth volume of Secret Coders. This wildly entertaining series combines logic puzzles and basic coding instruction with a page-turning mystery plot!