An early generation starship enters geostationary planetary orbit around a desolate but potentially habitable planet, and begins offloading its colonists bred for this colony. The colonists set loose nanomachines to crumble the basalt covering the planet, then discover a volcano-looking structure that looks too symmetrical to be natural. When the advancing nanomachines reach this pseudovolcano, it collapses; the colonists realize there is an alien species on the planet and first contact has not gone well.
Click on any of the links above to see more books like this one.