In this second book of the trilogy, Tom must continue aiding Harlan Ames and the former slaves-now free citizens-of the Lunar Colony. As Harlan seeks answers to the disappearance and origin of the Empress in Tibet, Tom is working on a project to help both the colony and the entire state of California, both going through severe water shortages and both needing almost immediate relief His plan is to capture a water-laden comet from outside the orbit...