A multinational expedtion has landed, from their orbiting starship, Heavensbridge, on the planet Onogoro, a cold and dour world circling one star of a binary pair.  Their objective is to investigate a strange alien race, known to the human visitors as the Kybers.  These aliens, dwelling in a great network of ruined palaces, are partly biological creatures and partly machine, with the ability to switch themselves off at will, thus appearing to "die" periodically.

The expedition's linguist, a beautiful Japanese, and the impulsive Andrik Norn, aspiring specialist in alien behaviour, are together drawn into a fierce know of passion and ultimate betrayal as they struggle to understand the strange origin and motives of the aliens -- which, if true, could shatter humanity's concept of the universe.  Meanwhile, other expedition scientists discover that the Kybers' sun is soon to blaze up in a nova.  Yet the Kybers. when told this are not alarmed . . .
[From the flyleaf of the Readers Union edition]

Dedication:
To Greg Benford