When the students in her middle school become obsessed with a new website called SlamBook, Faith Taylor decides to find out which classmates are leaving negative posts and retaliates with her own harmful comments.

The Coders uncover a clue that may lead them to Hopper's missing dad, but they may need to use Professor Bee's Turtle of Light to find him.

Looking forward to joining the new coding club at school so that she can develop her app idea, Lucy is disappointed by the lukewarm reception she receives from the club's other members, who work with her to decipher mysterious coding notes.

Determined to learn the history of once-elite Stately Academy, Hopper, Eni, and Josh are challenged to outmaneuver Principal Dean, who demands that the team turn over their most powerful robot and threatening coding genius, Professor One-Zero.

To save humanity, Hopper, Eni, and Josh must travel to Flatland, a dangerous two-dimensional world ruled by polygons. If they can return home safely with a turtle of light, they might just stand a chance in their final showdown with Dr. One-Zero.