Set in A.D. 5406, the story begins on an Earth that has been occupied by the Qax, an amorphous lifeform that profits from information and technology trade, for four centuries. Jim Bolder, a space pilot on the run from creditors, accepts an assignment from the Qax through a human intermediary to determine just what the Xeelee are constructing at the center of the universe. Bolder is provided with a Xeelee nightfighter that can travel faster than light, and when he uses the drive, the stars around him appear blue -- the "blue shift" of the title.
As Bolder in the nightfighter approaches the Great Attractor, he discovers the Xeelee are constructing a massive ring from its matter, which they intend to use to flee the universe itself. But the Qax will not allow this information to be released, intending to keep it -- and a possible defense against the Xeelee -- for their own profit. Bolder dodges the Qax and launches a "starbreaker" that will gradually cause the Qax homeworld's sun to go nova, requiring them to divert their resources from the occupation of Earth, liberating the planet.
Blue-Shift is also the name of the second single-player expansion to Valve's Half-Life were you play the role of a security guard (Barney) instead of Gordon Freeman, attempting to escape Black Mesa Research Facility in the wake of a resonance cascade