Divergence
(The second book in the Heritage series)

In the aftermath of the "summertide" that nearly destroyed twin planets of Opal and Quake, a few humans and aliens representing various civilized worlds confront the remnants of an ancient technology and discover a threat to life as they know it. Excitement builds rapidly in this fast-paced sequel to Summertide (LJ 2/15/90). Recommended for large libraries.