The novel depicts a future in which galactic felons are dispatched to the prison planet Chthon to slave in fetid underground gem mines, with no hope of return. The anti-hero Aton Five, condemned for loving a minionette, acts as a catalyst for uncontrolled change, bringing chaos and destruction to this netherworld as he seeks to follow in the footsteps of the one man who, legend has it, somehow made his escape. As the miners penetrate deeper into the planet, they find that the planet is itself sentient.
The structure of the novel itself is unique. It is what Anthony has described as a "double hexagon. There are 8 sections divided into 2 parallel parts. Each part is composed of 3 parts equating to Aton's past (his childhood), his present (on the prison planet Chthon) and future.
Its sequel is Phthor.
Two additional novels in the series were written by Charles Platt, Plasm and Soma.