One winter evening just before Christmas, Stockholm is plunged into a sudden, citywide blackout. Radio, internet, phone service -- all cut out simultaneously, cloaking the city in darkness and silence.

On the pitch-black streets, a young woman carries a message for her estranged father. It may be the key to reversing the blackout and preventing further attacks. But someone powerful is determined to stop her from delivering it...

In an eerily quiet newsroom, journalist Christina Sandberg tries to piece together what's happening. She has a terrible feeling that, somehow, her ex-husband William is involved...

Code breaker and cyber-security expert William Sandberg recieved an anonymous email, immediately before the blackout, with very specific directions to be followed. His erstwhile colleagues in the state military police are very aware of this correspondence. Sandberg is taken into custody-just when he most needs to be in action to clear his name, find his daughter, and save the country from disaster.