Galactic Special Agent 253, Our Man From UMMO, is a playboy energy being from the center of a distant star, transmitted by a sentient psychedelic alien fungus. He is on a mission to identify, track down, and stop his predecessor, the former agent 253, a body-hopping terrorist named Mondo Cain, who uses classified information in his campaign against the galactic government. They end up on the Sol Wilderness Preserve And Theme Park, where the indiginous people (humans) aren't aware of the galactic government and staying in character is imperative for visitors -- a policy enforced by the death penalty. There is a complication regarding the fungus: the trip only lasts eight hours, after which hosts go back to their normal lives with a set of absurd fabricated memories; Agent 253 has no control over which host he ends up in: he has no consciousness while nobody in ~10 AU is currently tripping on the right drug, but he will hop to one at random when they start. He assumes his opponent has the same restriction. Eventually, he discovers that Cain is himself from the future -- if he hops onto a space-liner going near the speed of light in one direction & then hops onto another nearby spaceliner going in the opposite direction at the same speed, his consciousness ends up going back in time -- and that he discovered some dark secret about corruption in the galactic government. He pleads with his future self to reveal the information. Just when his future self is about to concede, a random passer-by shoots them both: an under cover agent, numbered 253, from Galactic Time Control.