At the end of the twenty-first century, Earth is under the control of a single intelligence, the apparently benign One True. Mars, meanwhile, is slowly terraforming, and the human settlers there are still free of One True's control...but they need a pressure suits to survive outside, and it will be a century or more before the planet's fit for terrestrial life.

Terpsichore Murray is growing up on Mars. She wants to quit school and become, like her father, an ecoprospector. He has other ideas: he wants her to stay in school. He does want her along on his next long trip but only to conduct a group of younger kids from the highlands at Mars's equator back to school in Wells City.

What happens next will change Terpsichore, will change Mars, and will open the door to a new chapter in the history of intelligent beings in the solar system . . . all of them.