Hopper, Eni, and Josh have used their basic programming skills to open secret passageways and defeat a gang of bullies, but in this third installment in the Secret Coders series, they're up against their toughest foe yet. While revealing some past secrets cluding hints about Hopper's missing dad ofessor Bess tells the trio about one of his former students, a talented but dangerously egomaniacal programmer. Now that former student is back, and the Coders will have to solve his programming puzzles and use their robot turtle helpers to stop him before he wages large-scale destruction. Since the start of the series, Yang and Holmes have offered plenty of programming lessons, and in this installment, the problems Eni, Hopper, and Josh d, in turn, the reader e called on to solve have become more complex, but the explanations and crystal-clear illustrations make them very comprehensible. Fans of the series will be happy to see yet another installment, and they'll be reassured by the ending that there are still more Secret Coders adventures to come.

The graphic novel series continues without preamble. The secret coders must use coding principles to overcome former Bee School student turned misguided do-gooder, Dr. One-Zero. Challenges presented build on skills from earlier episodes; this third book, with its clean comics style, creatively packages programming lessons within a story line that engages returning readers.

The series' overarching plot ramps up in the third entry of the Secret Coders series.With Professor Bee still stuck at the mercy of the villainous Principal Dean and his rugby goons in the cliffhanger that ended Paths and Portals (2016), friends Hopper (mixed race, Chinese/white), Eni (black), and Josh (light-skinned but racially ambiguous) must first program their way out of danger. After that situation is resolved, Hopper receives a warning that the principal is quite evil and that Hopper's mom might be in danger—but their mother-daughter communication still falters. Bee gives more coding lessons and also teaches the kids about his first students, among whom were Hopper's missing father and Pascal, a brilliant pupil who ended up building an army of robots for world domination. Although Bee, Hopper's father, and their team stopped him, Bee now worries that Pascal is back. Soon enough, Dean has Hopper's mom at gunpoint to force the coders to find a flying turtle that takes them right into the lair of a villain far worse than Dean. The coding principles focused on—parameters and Ifelse (if else) statements—are well-explained and -illustrated, which is necessary for readers to follow along with the characters' actions. The cliffhanger puzzle is an especially snazzy way to end this outing. Nearly every element (especially the bad guys) escalates wildly and successfully in this nifty comp-sci romp. (Graphic science fiction. 8-14)