Heechee Rendezvous
Frederik Pohl
 Robinette Broadhead returns in this novel, a married millionaire with health problems. However, he does not feel that he deserves transplants to keep him alive, still feeling guilt about his experience on a horrible journey to a black hole, many years ago. He still attempts to research more about the Heechee and their technology. At the same time, a madman named Wan attempts to search for his father within black holes, using stolen equipment and a Heechee ship. His probing is caught by a sentient race of slow-moving creatures who inform a Heechee patrol, sent out of their black hole to observe the state of the galaxy. Fearing that humans may alert a malevolent race of beings known as the Assassins, the Heechee patrol sets out to try to find out more about human achievements in space flight and whether or not the damage done by them can be undone. Wan's probing also releases Gelle-Klara Moynlin, a companion of Robinette on his journey to the black hole, from her two decade long entrapment, which for Moylin was really only several elapsed days. The journeys of these past and future friends of Robinette begin to converge, and in the end, humans finally meet the Heechee.