Lou Clark knows lots of things. She knows how many footsteps there are between the bus stop and home. She knows she likes working in The Buttered Bun tea shop and she knows she might not love her boyfriend Patrick.
When a freak cosmic event renders most of the Earth's population blind, Bill Masen - one of the lucky few to keep his sight - finds himself trapped in a London jammed with sightless mobs who prey on those who can still see . . .