The alternate timelines of Charles Stross's Empire Games trilogy have never been so entangled as in Invisible Sun, the techno-thriller follow up to Dark State, as stakes escalate in a conflict that could spell extermination for humanity across all known timelines.

Two twin worlds are waiting for war. America is caught in a deadly arms race with the USA, its high-tech, parallel world. Yet it might just self-combust first. For its president-equivalent has died, leaving a crippling power vacuum. Without the First Man's support, Miriam Burgeson faces a paranoid government opponent who he suspects of scheming to resurrect the American monarchy. And Miriam is indeed helping the exiled American princess. This is only to prevent her being used against America, but her rivals will twist anything to ruin her.

However, all factions will face a disaster bigger than anything they could imagine. In their drive to explore other timelines, high-tech America has awakened an alien threat. This force destroyed humanity on one version of earth-and if they don't take action, it will do the same to both America and the USA.