Hugo Award-winning hard science fiction master Greg Egan returns with
a new novel featuring one of science fiction's most unusual worlds.
Seth is a surveyor, along with his friend Theo, a leech-like creature
running through his skull who tells Seth what lies to his left and
right. Theo, in turn, relies on Seth for mobility, and for ordinary
vision looking forwards and backwards. Like everyone else in their
world, they are symbionts, depending on each other to survive.
In the universe containing Seth's world, light cannot travel in all
directions: there is a "dark cone" to the north and south. Seth can only
face to the east (or the west, if he tips his head backwards). If he
starts to turn to the north or south, his body stretches out across the
landscape, and to rotate as far as north-north-east is every bit as
impossible as accelerating to the speed of light.
Every living thing in Seth's world is in a state of perpetual migration
as they follow the sun's shifting orbit and the narrow habitable zone it
creates. Cities are being constantly disassembled at one edge and
rebuilt at the other, with surveyors mapping safe routes ahead.
But when Seth and Theo join an expedition to the edge of the habitable
zone, they discover a terrifying threat: a fissure in the surface of the
world, so deep and wide that no one can perceive its limits. As the
habitable zone continues to move, the migration will soon be blocked by
this unbridgeable void, and the expedition has only one option to save
its city from annihilation: descend into the unknown.
