The Free Lunch — Spider Robinson

PERIL IN PARADISE
Under the facade of the world's finest theme park lies a secret which could alter the course of human history.

Mike and Annie, refugees from the world outside, find a home underground, behind the scenes of Dreamworld, a theme park where hope exists as it does nowhere else. But Dreamworld is threatened by a jealous competitor who kills what he can't have. And if this were not trouble enough, Mike and Annie discover that each day there are more of the "trolls' who maintain Dreamworld than there were the day before. As the "trolls" continue to multiply, Mike and Annie must discover why....or it could mean the end of Dreamworld--and the real world.

Knotted in conflict and turmoil, what was a wonderful, carefree place, becomes a battleground on which the fate of Earth's future is at stake. And only Mike and Annie, two unconventional heroes, can save it.