Invisible Sun

The New American Commonwealth is caught in a deadly arms race with the USA, its rival in a parallel world. And the USA’s technology is decades ahead of the Commonwealth.
Yet the Commonweath might self-combust first – its leader has just died, leaving a crippling power vacuum. Now, in a power grab by her oldest adversary, Minister Miriam Burgeson faces allegations of treason.
But all factions soon confront a far greater danger.
In their drive to explore other timelines, the high-tech USA awakened an alien threat. This force destroyed humanity on one version of Earth. And if the two superpowers don’t take action, it will do the same to them.