After millennia had passed, Mankind discovered the Heechee legacy (an alien culture that fled to the reative safety of a black hole)--in particular an asteroid stocked with autonavigating spacecraft. Robinette Broadhead, who had led the expedition that unlocked the many secrets of Heechee technology, is now forced once more to make a perilous voyage into space--where the Heechee are waiting. And this time the future of Man is at stake....