On 26 September 1983, a Soviet early-warning satellite mistook sunlight on clouds for American missiles. In our world, a duty officer named Stanislav Petrov called it a false alarm. In this one, nobody did.
Finland, the most over-prepared nation on earth, had been getting ready for exactly that night. Hidden inside its brand-new NMT mobile-phone network was a secret digital network, years ahead of anything else in the world. In the fourteen minutes before impact, thousands of masts sang in unison and raised a shield over the country: the Lid. The world burned. Finland didn't.
Now it is 1988. Snow falls in July, the sky is an aurora-green dome, and the sun is only a projection on it. Every Finn carries a network chip implanted at birth, and the nation worships the network in the language of the Kalevala: masts are World Pillars, the core network is the Sampo, and hacking means singing a machine its origin-song.
You are Lemmi Saarelainen, a lineman-monk who keeps the masts singing. On a border mast you hear a song hidden in the signal, and you are murdered for it. Your mother, an illegal nano-healer, rakes you back from the dead. The network has deleted you — and someone is about to shrink the Lid and leave 800,000 people outside it.