The edge of madness - Michael Dobbs

Cyber-warfare: the kind that brings nations to their knees, switching off energy lifelines, crippling the financial markets, starving leaders of authority.
An old Russian nuclear reactor goes into Chernobyl-style meltdown while, on the other side of the world, the US Eastern Seaboard is plunged into darkness. No one knows - yet - who is responsible for the chaos.
Hidden from view of the rest of the world, an extraordinary meeting of the US President, the Russian President and the British Prime Minister is about to take place. They have the weekend to save the world - and they must do it alone.
Something serious is going on in Beijing. Military manoeuvres. Troops on the streets. It's as though the Chinese are preparing for the final thrust against their old enemies, bringing them to their knees in a war that will see not a single shot being fired.