Eight hundred years from now and a hundred light years from Earth, at the periphery of a vast interstellar civilization, humanity itself is changing-each individual injected at birth with 'nanites, ' marvels of nanoscale technology that function in ways that are indispensable for almost every important transaction in life. This nexus between biology and technology is at the point of transforming the core of what it means to be human, with the next generation of nanites to impinge on the very thoughts of Homo sapiens.

Not everyone acquiesces to this vision of what humanity is becoming. The Free Range-at the far fringes of the colonized Spiral Arm and settled by individualists, free-thinkers, humanists-opposes this biomechanization of the spirit, to the death. Their struggle to preserve their own identity, their faiths, to prevent the hivemind from overcoming their culture as well, has given rise to a terrific resistance which, unfortunately for the free rangers, is ending badly.

One young free ranger, Enguerrand Duprey, has been abducted and compelled to act as bounty hunter for one of the most powerful men among hundreds of billions. The impossible realm into which Enguerrand is sent and the unfathomable quarry he is forced to seek sets off a series of events that strains the very fabric of the cosmos itself, daring to put effect before cause and setting into motion the most frightening event imaginable, one that will change not one universe, but two, and exposing something age-changing about the very nature of nature itself.