The Legacy of Heorot by Larry Niven, Jerry Pournelle and Steven Barnes; maps by Alexis Walser (Simon & Schuster: $17.95; 367 pp., illustrated)

At first, the idea of reworking the Beowulf legend on a science fiction theme appears specious, if not ludicrous. After all, the ancient Teutonic tribes that retained the legend orally and the Celtic scribes who recorded it were deadly serious in their efforts to preserve the tale of the warrior-king who slew monsters and dragons in order that civilization might survive. This noble myth would seem inappropriate, at best, in outer space. But “The Legacy of Heorot� undertakes that presumptuous exercise not only without disappointment but with substantial success.

The authors have begun their work cleverly by adhering as closely as possible to the ancient names associated with “Beowulf.� Originally, Heorot was the Great Hall of Hrothgar, the king whose thanes were plagued by the monster Grendel. In this book, Heorot finds another, more modern and more sinister, meaning. The planet that the interstellar colonists inhabit is called Avalon, after the idyllic home of King Arthur. The protagonist is Cadmann Weyland, referring to the early English poet Caedmon, whose poems based on stories from the Bible became sacred legends, and Wiglaf, the sole fellow warrior attending Beowulf’s death. Indeed, “The Legacy of Heorot� begins with Beowulf’s dying words to Wiglaf:

Thou must now look to

the needs of the nation

Here dwell I no longer

for Destiny calleth me!

In this updated tale, Avalon is populated by a select group of volunteer space pioneers in the 21st Century. Each person possesses at least two skills crucial to the construction and maintenance of civilization. Cadmann’s skills are leadership and weaponry. Initially held in awe by virtue of his expertise and courage, his fellows later find him an anachronism as their chosen site for Earth’s first experimental space colony proves more and more bucolic. Apart from the presence of two moons, a bluer sky and a heavier gravity, Avalon appears almost absurdly comfortable. Cadmann’s reminders to the colonists that they live in an alien world fall on deaf ears. Very quickly, their foolish trust in the foreign environment results in deadly pandemonium.

Predictably, there appear the futuristic equivalents to Grendel and his mother. The safety of the colony is threatened in the most graphic terms, as small animals begin to disappear, leaving signs of terrible carnage in their wake. Cadmann is suddenly in favor again. All the technology that these elite scientists can muster is summoned to defend themselves and their territory. Led by Cadmann, horrific battles are fought, leaving the colonists victorious, but decimated. Injured and weary, sobered by both internal and external conflict, the colonists set about burying their dead and rebuilding their camp. With the planet Earth 10 light years away, they have little choice but to persevere. Under their very noses, there lurks and grows to maturity a disaster of Gargantuan proportions.

Far from preposterous, these monsters are no more irrational to contemplate than the originals. In fact, there are probably more parallels between the past and the future in general than is conducive to tranquillity.

“The Legacy of Heorot� is riddled with science fiction jargon, yet opens each chapter with quotations from classical literature and philosophy. Cadmann sings in Welsh. At every turn of the plot, there are point and counterpoint. The authors have taken great pains to produce a convincing story analogous to the legend of Beowulf in its symbolic representation of good and evil, the familiar and the unknown.

Special mention should be made to the maps by Alexis Walser. It is as though she herself were persuaded that Avalon and its colonists exist in the present, along with the terrible threat to that existence.