Heroic colonists from Earth battle bug-eyed monsters on an alien planet: remarkable that it took three authors to put together this sometimes exciting but fundamentally unsound package. The two hundred colonists of planet Avalon, some brain-damaged after their long journey in suspended animation, have built a thriving community on a large island, while disregarding the dire warnings uttered by security chief Cadmann Weyland. But Weyland--so obviously it clanks--turns out to be right: up from the nearby river pops a ""grendel,"" a dinosaur-like predator with a metabolic supercharger that permits it to roar around the landscape at speeds slightly less than Mach One while shredding steel plates like damp newspaper and generally committing mayhem. Shocked, the colonists gear themselves up to root out and destroy the handful of grendels on the island. All's well--or is it? No, indeed. The colonists have made a disastrous miscalculation regarding the local ecology--and soon the colony is beset by swarms of young hungry grendels. Fast and furious monster-bashing, with a romance or two thrown in: exciting for about half, thereafter increasingly gory and tedious, what with the ecological puzzles that don't add up and the absurdly pretentious quotes and allusions. Too much brawn, not enough brain.