It's no secret that Jack disapproves of the new piledriver equipment Scharnhorst is using to mine the interior. When the equipment is stolen, Scharnhorst accuses Jack - and because a corrupt City guard has taken the evidence that shows the crime was committed by Hammer Terhune, Jack is sentenced to a wilderness gulag. When he escapes en route to stop Hammer from turning the piledriver into a poaching weapon, Jack becomes a fugitive, and Scharnhorst recruits a relentless bounty hunter to track him down...

At an outdoor market run by the Moles, Hannah learns that Scharnhorst and Fesseden have accessed a high-tech cybernetics lab. When she tries to access the lab herself, she is captured by city guards; it takes Jack disguised as such a guard to liberate her. Fesseden activates the lab's dangerous tunneling robots, which seem to have minds of their own, and immediately make moves to break out of the compound. In the ensuing battle, Jack and Hannah elude Scharnhorst and, with the help of the Moles, bring the underground lab crashing down on the unstoppable machines.

Using dynamite stolen from a deep-woods scavenger to scare up a pack of dinosaurs, the Terhune brothers inadvertently set off a huge blaze in the middle of the jungle.. which quickly spreads, approaching Scharnhorst's new gas wells. The only way to stop the blaze before it reaches the wells and ignites the entire jungle is to bury it under tons of dirt and rubble... and the only way to do that is to use Scharnhorst's store of unstable nitro-glycerin. In a race against time, Jack and Hannah must reluctantly join forces with Scharnhorst and the Terhunes to transport the nitro to the appropriate blast zones.. a process made twice as deadly by the scavenger, who has returned to exact revenge on the Terhune brothers.

Jack and Hannah are hunted in the deep jungle by a cunning Poacher, hired by Scharnhorst to prevent them from meddling with her plans to excavate an ancient train station/railroad line. The situation becomes even more dangerous when the excavation crew unwittingly looses an ancient plague....to which only Hannah has the antidote.

Jack is reunited with his cocky childhood friend Sean Russel, another Mechanic who tells Jack he's considering relocating to this area. Though they are still close friends, Jack never quite got over a dangerous game of chicken which he lost to Sean when he was young, and Hannah has a suspicious feeling about him. Sure enough: Sean has stolen a crystal from the Grith, which can be used to control dinosaurs and which is vital to keeping Grith alive. Sean is using the crystal to corral the dinosaurs for eventual poaching. He is pursued by the shocked and furious Jack, and again they face each other in a deadly competition, this time as mortal enemies...

Scharnhorst and Dr. Fesseden discover the control facility for an SDI ballistic-laser satellite, deep within Girth territory; this attracts the attention of both Jack and Hannah and the Poachers, and soon a three-way battle for control over the facility ensues. With a little help from the Grith, Jack manages to program the satellite to destroy the control facility, since this is the kind of "knowledge" he believes everyone is better off without.

The Poachers launch a massive attack on Jack's Garage in an attempt to take it over and exploit its weapons and technical riches. Mikla poses as an escaped captive of the Poachers in order to infiltrate the Garage and sabotage its defenses. Jack's cleverness and the Poachers' lack thereof - foil the attack, and the Poachers are all driven back into the jungle, Mikla included.

Jack, Hannah and Moustapha try to unravel the "Loch Ness Monster" -style mystery of a nocturnal creature, roaming the streets of City in the Sea and capturing its citizens. Despite difficulty from Scharnhorst, who doesn't believe the creature exists, they discover that it's a special kind of dinosaur called a Thecodont, and it's capturing the city-dwellers to use as food for its young.

While escaping a rampaging T-Rex, Jack and Hannah come across a large metallic capsule... containing an Ancient in perfect cryogenic storage!! It soon becomes apparent to Jack that there's something strange about this fellow Adamas, though the smitten Hannah is quick to disagree. As it turns out, Adamas is an android, created by the Army Corps of Engineers shortly before the Upheavals. When Scharnhorst learns of Adamas' vast library of technical knowledge and super-strength, a vicious tug-of-war ensues... Adamas, caught between the forces of good and evil, soon he concludes that the only solution is to go back into suspended animation, until such a time when the world will be better prepared for his powers.

Hannah's plan to house pteranodons in the City as a warning system against dangerous sea lizards is met with furious opposition from Scharnhorst, and frank skepticism from Jack. Hurt and upset, Hannah accepts a Wassoon promotion that will recall her to her homeland, resulting in mixed feelings for Jack and Hannah both. Their trip back through the interior is disrupted by a power-mad despot and his monstrous War Wagon... only Jack and a reluctant Hannah can stop him from destroying the city. Their adventures and the success of Hannah's warning system lead her to reconsider her rash decision to leave.