Like many of Bayley's books, The Zen Gun is space opera with all the conventional trappings: a declining, anthropocentric, Galactic empire loses its grasp on power as it slips into the Long Night of civilization, star fleets with the ability to ravage worlds warp through the void at superluminal velocity and a hyperweapon threatens to end life itself.

However, Bayley extensively reworks these ideas for the purposes of his novel: the humans of the galactic empire are seen to have ceded most of their imperial power to evolved animals in an attempt to prolong their decadent existence, Admiral Archier's starfleet has been despatched to collect overdue taxes from colony worlds, the empire have ripped a hole in the fabric of reality and the pseudoscientific belief that gravity is repulsive rather than attractive is literally true.

The events of the primary plotline are instigated by a message from Archier's Oracle, which alerts him to the existence of the Zen Gun, a weapon capable of destroying suns, which the chimeric, human-hating Pout wishes to use to annihilate the empire.

"[1] Bruce Sterling enthused extensively about the novel in the legendary fanzine Cheap Truth: "Yet Bayley's elemental energy, his mastery of the sense of wonder, cannot be denied.

To invent an entire self-consistent cosmology and physics for a $2.50 DAW paperback (THE ZEN GUN, 1983) is one of those noble acts of selfless altruism that keep SF alive."