The planet of Krishna is hardly ready for the first shipload of Earthside tourists from the Magic Carpet Travel Agency--a dozen noisy individualists including a German camera fiend, a resident nymphomaniac, a pair of cooing homosexuals, a retired black schoolteacher of furious political convictions, and a wise-guy with exceedingly light fingers. Fitfully restrained by the efforts of weary tour-guide Fergus Reith, the Magic Carpeters swarm through this pre-industrial world of olive-green hominids, photogenic temples, and enterprising robber barons. Mostly this is a cheerful sci-fi If This Is Tuesday. . . , punctuated by embarrassing run-ins with indignant Krishnans and howls of ""I want my money back."" Unfortunately de Camp has also seen fit to work in a plot, a ragged and witless affair involving guerrilla kidnapings, the cult of the local ""witch,"" various dynastic squabbles, and much sniggering sex. And the de Camp prose style has never been more slapdash and perfunctory. Nice idea, lousy execution.