Zephaniah Corcoran has just returned to Earth after a seven-year jaunt to Jupiter where his special--some would say dubious--talents were put to the test in attempted communication with the Jovian cloud-whales. With no time to adjust to life on an Earth half alarmed and half fatalistic at the prospect of final catastrophe, he is headhunted for a reprise of his old job: being projected by the brilliant but asocial Walter Halleck's Coincidence-driven Sling into the far future to make empathic contact with the various successors to the human race. In the meantime, he is discovering a close and mysterious bond with Denise, a doctor of evolutionary biology and the younger sister he has hardly known, who has been noticed by the same big players who have noticed Zeph. But nothing goes quite according to plan, and as the fate of humanity dangles on a thread grown very frayed, Zeph's empathic skills are expanded in unexpected ways, not so much by coincidence, as by Coincidence, bringing Zeph and those around him into contact with what are perhaps only the beginning of ongoing revelations of time and space whose grandeur match the universe that Zeph and his colleagues must now begin to explore.