In the year 2240 AD, the human race has migrated to the far reaches of the solar system, but that hasn't ended conflicts among the many human outposts separated by vast stretches of space. Earth, devastated by climate change, has become a corporate state where governments are a mere proxy for corporate interests. The Saturn Commonwealth, a billion miles from the corporate centers of power, is the only remaining free human society in the solar system.
Serena Roe, once an indentured corporate super-soldier, now a disgraced corporate contract laborer, finds herself encased in a block of methane ice two kilometers below the surface of Titan, Saturn's largest moon. She becomes the victim of sabotage on Commonwealth territory by unknown forces. A dark figure hovering above her destroys her communications system and leaves her to die. So starts Serena's journey to try and discover who's trying to kill her, which leads to the discovery of a god-like power from deep-time, and the murderous plans of Adonus, a high corporate officer.
What follows is a lethal chess match between a lone, highly advanced Commonwealth cruiser, the Vindicator, which is equipped with sentient intelligence, and Adonus's on-site forces, supported by a powerful corporate fleet carrying anti-matter weapons. Adonus is determined to use the super technology of the alien artifact to destroy the nascent but powerful Commonwealth. Adonus discovers they cannot move the artifact off Titan, which ignites an all-out war on Titan, in Saturn space, and aboard the corporate assault ship, Athena. While all this is happening, Serena is having disturbing dreams, which compel her to sneak back to the site of the accident that trapped her in the ice. She uses a route under a methane sea adjacent to the site in an attempt to discover the secret of Adonus's discovery and the key to the survival of the Commonwealth.