Sarah has a book, and she is not afraid to use it. She wants to know more about the universe than what the Elders seem to know. There are powers waiting for her outside the simple village life that is all she has known. From orbit, Captain Marshall is on the lookout for someone like her. Genetic engineering gone wrong came close to making humans extinct. Everyone thought telepathy would bring new ways of solving humanity's problems. At last, an egalitarian society beckoned. Instead, the enhancements unleashed a psychotic storm of violence. The Great Catastrophe had befallen human society. When people saw the mundane evil of their neighbours they went on the attack. Everywhere, people turned on one another. The killing went on unabated until a fix reversed some of the damage done. Humanity had to leave Earth behind. The risk has hardly lessened in more than three hundred years of resettlement. Sarah's explorations threaten to undo the truce in killing. Now Captain Marshall must deal with her all alone.