The story is set on Tau Ceti 4, a planet recently colonized by an expedition from earth. The planet’s new inhabitants set up their base on an island which appears to be devoid of animal life except for a couple of harmless creatures. The Earth crops and animals grow well. People are happy, life is good.
As head of security, Cadmann Weyland would seem to have the easiest job on the planet. But he refuses to be complacent and demands fences and other security measures to ensure the safety of the colony.
The other colonists accept these measures with varying degrees of resistance, but Weyland is generally regarded as a bit over the top.
Until the deaths start.
When I first started reading sci fi as an adult this was the first book I read, and it proved to be a real page turner. A sequel The Dragons of Heorot was written in 1995.