Genetic engineer Noah Parker helped domesticate dragons for use as pets and deployed them for the United States military. Now his team is tasked with designing dragons to tackle invasive species and other ecological problems. It's no easy job, especially because government approval requires the dragons have built-in failsafes to prevent them from reproducing in the wild. To Noah's surprise, the approval also requires the presence of an onsite observer—who happens to be his former rival from graduate school.

Still, there are big problems to solve where dragons can help: from a plague of locusts threatening a precious desert oasis to a rat infestation in penguin nesting habitats in Antarctica. Every environment brings unique challenges, ones that Noah can only understand by going there in person. All that remains is watching to make sure dragons get the job done.

Although the environmental control dragons are successful, the Build-A-Dragon Company starts to receive worrisome reports of wild dragons in places they should not be. Many of those point to a small Midwestern town where dragons have attacked livestock and even people. When Noah travels there to investigate, he finds the problem is far worse than they could have imagined . . .