Fool's Run, by Patricia A. McKillip. New York: Warner Books. 221 pp. $15.95. This book is so beautifully conceived and produced that it is almost as much high art as high-tech. Images of extra-galactic life taking unspeakable shape overwhelm the mind of Terra Viridian and reach across space to Magic Man the Bach master, Sydney the space musicologist, a masked Queen of Hearts, and a heart-frozen patroller named Aaron who watches over them like an intergalactic angel. These helplessly empathetic friends and lovers are driven before invasive projections of alien urgency. ``Fool's Run'' is an original composition that is no more describable than the mystery it spins around. Stalking the Unicorn: A Fable of Tonight, by Mike Resnick. New York: TOR. 312 pp. $3.50.
``You little green wart'' is M"urgenst"urm, the devious elf who cons an Irish shamus into a wild unicorn chase in the ``other'' Manhattan - a parallel Big Apple even more rotten than our own. Resnick's wisecracking detective (via Fritz Leiber's famous fun-fantasy series about Fafhrd and the Grey Mouser) recruits Mephisto the paranoid mage (his magic mirror hates him), Felina the catperson, and a unicorn expert retired to the Morbidium, where warehoused residents sleep comfortably in upholstered coffins with built-in stereo. John Justin Mallory of the significant middle name saves both our world and six-inch Eohippus, who is shrunk by blows to any horse anywhere - as all of us are diminished by human cruelty anywhere. ``Stalking the Unicorn'' is hilarious, profound, and magical. Twisting the Rope, by R.A. MacAvoy. New York: Bantam Books, 1986. 242 pp. $3.50.
For readers who enjoyed taking ``Tea with the Black Dragon,'' he is back - ageless, ancient, and still stuck on Martha MacNamara, a feisty fiddler in her 50s who leads her kooky musicians (called MacNamara's band, of course) through some Celtic loony tunes on California's barbarous coast. The murder of the group's piper entwines them all with the secrets of the living and the dead - and of someone in between who takes over the mind of the heroine's three-year-old granddaughter. Strands of love and hate are woven into ``Twisting the Rope.'' When the mystery is solved, Martha agrees to tie the knot with her silken-mannered Mayland Long: Is MacAvoy roping readers into a series featuring the graying musician and her elegantly deadly mate? Firecode, by Chelsea Quinn Yarbro. New York Popular Library. 453 pp. $3.95.
Readers who regularly ``input'' 15-digit number strings may be looking around their terminals uneasily indeed, for Yarbro has combined the ancient cabalistic notion of mathematical codes with modern dependence on computerized devices that crunch numbers ad infinitum. The numerology of the fire demon (FIRECODE) is unwittingly fed into everything from preprogrammed microwave ovens to government main-frames by people who definitely do not know the number of this beast. Public and private agencies fight the flames, each other, and any acknowledgment of what is happening. Yarbro's careful probing into the lives of people whose numbers are literally up - on the computer screen - makes readers all the more vulnerable to the impact of her literally burning question: ``What if...?''