Flint, green-skinned Stone Age native of Outworld, one of the Empire's most remote planets, has just killed the dinosaur Old Snout and saved his tribe. All he wants to do is enjoy his victory -- and his woman, Honeybloom. But the Empire has other plans.
The alien envoy Pnotl of Sphere Knyfh has come seeking help from Sphere Sol in a shared galactic‑level crisis: Galaxy Andromeda has discovered the secret of energy transfer and intends to use it to steal the basic energy of the Milky Way Galaxy. Knyfh offers the secret of Kirlian aura transfer on the understanding that Sphere Sol will spread the technology to help create a galactic coalition to find and defeat agents of Andromeda. Sol's highest‑Kirlian individual is Flint, whose Kirlian aura of two hundred, high (though uneducated) intelligence, and eidetic memory make him the ideal agent. His task is complicated, however, by the fact that he is pursued everywhere by a high-Kirlian female Andromedan assassin, turning his mission into a combination of high-tech science, diplomacy, and espionage.