The Covenant mission is the most ambitious endeavor in the history of Weyland-Yutani. A ship bound for Origae-6, carrying 2,000 colonists beyond the limits of known space, this is a make-or-break investment for the corporation - and for the future of all mankind. Yet there are those who would die to stop the mission. As the colony ship hovers in Earth orbit, several violent events reveal a deadly conspiracy to sabotage the launch.

Ellen Ripley finally returns to Earth, only to discover that LV-426 — where the crew of the Nostromo first came into contact with the deadly xenomorphs — has been renamed Acheron. Protected by Colonial Marines, the colonists seek to terraform the storm-swept planet against all the odds. But in the face of brutal living conditions and the daily struggles of a new world, there is humanity and hope.

Deep in the African rain forest, near the legendary ruins of the Lost City of Zinj, an expedition of eight American geologists are mysteriously and brutally killed in a matter of minutes. Ten thousand miles away, Karen Ross, the Congo Project Supervisor, watches a gruesome video transmission of the aftermath: a camp destroyed, tents crushed and torn, equipment scattered in the mud alongside dead bodies - all motionless except for one moving image - a grainy, dark, man-shaped blur.

Ryland Grace is the sole survivor on a desperate, last-chance mission - and if he fails, humanity and the Earth itself will perish. Except that right now, he doesn't know that. He can't even remember his own name, let alone the nature of his assignment or how to complete it. All he knows is that he's been asleep for a very, very long time. And he's just been awakened to find himself millions of miles from home, with nothing but two corpses for company.

The United States government is given a warning by the preeminent biophysicists in the country: current sterilization procedures applied to returning space probes may be inadequate to guarantee uncontaminated re-entry to the atmosphere.