Heinlein's back in form, with a most refreshing and satisfying blend of ideas and storytelling. Church fundraiser and lovable bigot Alex Hergensheimer, on an ocean cruise through Polynesia, follows (on a bet) some native firewalkers across a bed of burning coals, then collapses unconscious--and wakes in a parallel Earth, where he has the identity of shady wheeler-dealer Alec Graham. His shipboard beloved, Danish maid Margrethe, sees no difference in him, and Alex/Alec suspects his sanity--until one night the ship strikes an iceberg (!) and he and Margrethe are washed overboard, naked, into another alternate world. And this is just the prelude to a whole series of world-shifts, wherein Alee and Margrethe usually arrive unclad and penniless, surviving by their wits and menial toil. Despite their plight, Alec's faith in God and the Bible never wavers (though he does rail at whatever cosmic prankster is persecuting him); he concludes that Judgement Day is approaching, and warns those who will listen to repent. Eventually the Last Trumpet does indeed sound: Alec is summoned bodily up into heaven, becoming (to his astonishment) a saint; but Margrethe is nowhere to be found, so poor Alec descends into hell, feeling ever more Job-like; and a sympathetic and helpful Satan finally takes Alec before an ineffable being (a super-God), who agrees that Alec's faith has been tested and found true. . . and sets everything to rights, Margrethe-wise. Despite a few jarring or illogical moments: a limber, complex, and economical novel that disarms and often compels--with Heinlein's best theology-shaded fantasy since Stranger in a Strange Land.