OFFSHORE, THE MAN WATCHED THE EVENTS ON THE island through his binoculars. His boat was camouflaged, and he positioned it behind a small patch of saw grass clinging to a mound of soil sticking up out of the water. His pets were behaving strangely. It wasn’t like them to take an interest in anything that wasn’t a snake.

Still, he was reluctant to act. He wouldn’t allow the boys to come to any real harm. But carefully managed, this situation could work to his advantage. If Dr. Geaux believed that more of his creations roamed the swamp, she would proceed with caution. Perhaps even taking the unprecedented step of closing the Everglades to all visitors. Which was his ultimate goal. He intended to restore the ecosystem there to its original pristine state. Nothing less would satisfy him.

He watched as the hybrids crept across the sand toward the airboat. Calvin was a cool customer, not panicking like most boys his age would. They were out of earshot, but he could see them talking and hear the muffled sounds of their raised voices.

Now he studied his creations’ behavior as they approached the boat. Seeing them act this way was mildly alarming. His intention was for the boys to be frightened off by the rustling in the bushes and the unique sound of their fearsome call. For some reason, Hammer and Nails left the cover of the trees, now acting as if they would attack the boys. He decided to let them get a little closer before activating their beacons. But hopefully this field observation would give him some insight into why one of his specimens now lay dead in Dr. Geaux’s lab.

Could it be the constant and infernal barking of the dog? Did the noise awaken some primitive avian or reptilian response, which caused their genetically altered brains to focus on the canine? Might that be what happened to the earlier specimen Dr. Geaux found? His data said it was highly unlikely. Carefully controlled tests showed that the creatures fixated solely on pythons and boa constrictors. Even when offered an easier opportunity for prey, they were fed only snake meat from the time they hatched. The avian strain of the great gray owl, a bird of prey known for its love of snakes, had overridden the alligators’ desire to eat the easiest thing to catch. Given that raptors like the owl could be trained, he was certain he had created the perfect snake-killing machine.

So why were they reacting this way?

Hammer and Nails were now almost at the boat. One of the boys was using the boat hook to pole the boat backward into the water. Perhaps it was a mistake to disable their boat and take the microphone. All he wanted to do was put a healthy scare into them.

The dog was nearly crazed now and barking so much its voice was growing hoarse. The creatures were at the water’s edge and seemed fixated on the black-haired mutt. It was time to reassert control of the situation.

He pressed the button on the console that activated their homing collars. Hammer and Nails stopped and looked in the direction of his boat. They backed up on the sandy shore and held still, appearing confused. Their heads swiveled back and forth, looking at the nearby boat and toward his position.

Frantically, his fingers flew over the tablet, adjusting the beacon’s intensity and frequency. The two Pterogators still did not respond. To his horror, they ignored his signal and turned their attention back to the boys, the dog, and their stranded boat.