When Geeker morphs into a dinosaur and finds himself unable to change back, Noah must hide him in Dinopolis, the hidden city of the Dinosaurs where no human is allowed. But this brings the wrath of Mister Moloch down on Dinos everywhere, and soon Noah must choose between protecting his friend and saving his people.

A strange monster is wreaking havoc on the city of Neo-Denaire. Becky and Noah are shocked to discover the the ""monster"" is actually a sleep-walking GeeKeR. Noah learns the cause of GeeKeR's Jekyll-and-Hyde transformations; a signal beamed at GeeKeR from an orbiting satellite. But GeeKeR is forced to stay awake to avoid becoming a monster, and his sleep deprivation-induced hallucinations cause no end of trouble for our trio.

Doctor Maston implants a tracer in Noah so that Mister Moloch can track him and capture GeeKeR. But the tracer affects Noah's brain, causing him to gradually revert to savagery. Noah soon goes off on a berserk rampage, and Becky and GeeKeR have to track him down. But when they find him, they discover that the nine-foot dino would just as soon chow down on friends as strangers.