from the back of the book:
A million years ago, a powerful alien species moved a dead planet into the narrow life-support zone of an old, cold class M0 star. Then it gave the world an atmosphere, settled its surface with a bizarre mixture of creatures - some long since vanished from Earth - erected marvelous hivelike cities, and disappeared.
But Hunanity's arrival had apparently set the planet's hidden machinery to working. The dead cities had begun to glow at night and even the animals were undergoing startling transformations.
So Dorthy Yoshida, astronomer and reluctant telepath, was summoned from self-imposed exile near distant Earth and set to search for the mind that moved the world.