An egregiously silly ""hollow Earth"" yarn from editor-critic Knight, his first novel since Beyond the Barrier (1964). The sun's going nova--so Earth, given an air-and-heat-retaining shield, is hollowed out, fitted with engines, and sent scooting off into space in search of more congenial conditions. . . only to find war and Armageddon. So what will young surface-dweller Thorinn discover when he's stuffed down a dry well by his foster-family to appease the gods (with a spell compelling him to continue downwards)? The answer--as recounted in turbid pseudo-Saga-ish prose (""Then for weariness alone he forebore"") and fatuous dialogue--is that dreary Thorinn discovers tunnels and caverns where various dull and unpleasant creatures (""twigmen,"" ""gray demons,"" ""wingmen"") lurk, not to mention the odd bothersome whizzing machine. And along the way he acquires ""the box,"" a sort of moronic talking TV set; arriving eventually at the Earth's center, Thorinn and box fall foul of the Monitor, a schoolmarmish computer who still runs things underground and imprisons our hero. But, after some banal wrangling, it emerges that Thorinn is really the long-lost king of the surface-dwelling Skryllings. Feeble fantasy--from a writer whose fine short stories and editorial acumen have always counted more than his disappointing novels.