A return voyage to the astonishing world of Larry Niven's Ringworld, with even more remarkable adventures and surprises, and a solution to that tantalizing question left from the earlier book: how was Ringworld built and by whom? It's been twenty years since the quixotic and worldsweary Louis Wu discovered the Ringworld. Now he and Speaker-To-Animals are going back, captives of the Hindmost, a deposed puppeteer leader. With Louis' help, the Hindmost intends to regain his status by bringing back such extraordinary treasures from the Ringworld that his fellow puppeteers will have to be impressed. But when they arrive, Louis discovers that the Ringworld is no longer stable . . . and will destroy itself within months. To survive he must locate the control center of the legendary engineers who built the planet.