Peacemaker (Peacemaker #1)

Virgin Jackson is the senior ranger in Birrimun Park - the world's last natural landscape, overshadowed though it is by a sprawling coastal megacity. She maintains public safety and order in the park, but her bosses have brought out a hotshot cowboy to help her catch some drug runners who are affecting tourism. She senses the company is holding something back from her, and she's not keen on working with an outsider like Nate Sixkiller.

When an imaginary animal from her troubled teenage years reappears, Virgin takes it to mean one of two things: a breakdown (hers!) or a warning. Dead bodies start piling up around her, so she decides on the latter. Something terrible is about to happen in the park and Virgin and her new partner, U.S. Marshall Nate Sixkiller, are standing in its path...