Total eclipse — John Brunner

Nineteen light years from Earth, on Sigma Draconis, an international space team stumbles upon the first evidence of another highly advanced civilization in the universe.

Tragically, however, the Draconians are extinct and have been for a hundred thousand years. What mysterious disaster destroyed man's nearest neighbour in the colossal emptiness of space? And will the same fate befall Earth?

The answers, as Earth degenerates into squabbles, paranoia and self-destruction, are vital. But how to begin the almost insuperable task of cracking the enigma of a long-buried and utterly alien culture?