Science fiction masters Larry Niven and Gregory Benford continue the thrilling adventure of a human expedition to another star system that is jeopardized by an encounter with an astonishingly immense artifact in interstellar space: a bowl-shaped structure cupping a star, with a habitable area equivalent to many millions of Earths. Investigating the Bowl, or Shipstar, the human explorers are separated-one group captured by the gigantic structure's alien inhabitants, the other pursued across its strange and dangerous landscape-while the mystery of the Shipstar's origins and purpose propel the human voyagers toward discoveries that transform their understanding of their place in the universe.