A first contact SF novel, from the Hugo Award–winning author of Folding Beijing. 2080, the world is divided, dominated by two antagonistic factions, the Pacific League and the Atlantic Alliance. Tensions are high and the smallest disturbance in the status quo could set the world on fire. And a signal flickering through deep space could be just that spark. As three young scientists form an alliance to decode the signal, they realise that the answers don't only lie in deep space, they also lie deep in humanity's past. What they discover will change everything: our past, present and future. If we have one.