In StarCraft: Evolution, the war between the terrans, the protoss, and the zerg has been over for years, but the fight for peace is still being waged. As the Terran Dominion struggles to recover from the ravages of war, Emperor Valerian Mengsk has no intention of ruling in the same bloody manner as his father, the late Arcturus. Instead of seeking vengeance, Valerian is determined to maintain the peace. So when he receives an urgent plea for aid from Zagara, Overqueen of the savage zerg Swarm, he agrees to hear her case despite his personal misgivings and the severe disapproval of Hierarch Artanis of the protoss.
Zagara claims that the Swarm has changed. No longer bent on destruction, they have revitalized the planet Gystt, once thought to be irreparable after its incineration by the protoss during wartime. Now the zerg wish only to live there in peace and nurture new life. But when Dominion agents—a hard-bitten marine, an unpredictable reaper, an idealistic xenobiologist, a former ghost operative, and an enigmatic protoss researcher—arrive to investigate the planet, they suspect that not all of the zerg are truly dedicated to Zagara’s dream of harmonious paradise. Gystt hides dark secrets, and should they be unleashed, it will mean disaster for the universe.