Larry Niven teams up with fellow science fiction writer Edward M. Lerner to take a closer look at the events leading up to Niven's first Ringworld novel.

Kirsten Quinn-Kovacs is among the best and brightest of her people. She gratefully serves the gentle race that rescued her ancestors from a dying starship and nurtures them still. If only the Citizens knew where Kirsten's people came from!

A chain reaction of supernovae at the galaxy's core has unleashed a wave of lethal radiation that will sterilize the galaxy. The Citizens flee, taking with them their planets, the Fleet of Worlds. Someone must scout ahead, and Kirsten and her crew eagerly volunteer. Under the guiding eye of Nessus, their Citizen mentor, they set out to explore for any possible dangers in the Fleet's path—and uncover long-hidden truths that will shake the foundations of worlds.