"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...

Tchicaya and his spaceship Rindler are the center of scientific study of a newly created vacuum in space. He soon finds himself the focus of a fierce conflict between a faction that wants to study and preserve the vacuum and one that wants to destroy it.

Since the Introdus in the twenty-first century, humanity has reconfigured itself drastically. Most chose immortality, joining the polises to become conscious software. Others opted for gleisners: disposable, renewable robotic bodies that remain in contact with the physical world of force and friction. Many of these have left the solar system forever in fusion-drive starships. And there are the holdouts: the fleshers left behind in the muck and jungle...