THE BOOK OF SORROWS is the sequel and conclusion to The Book of the Dun Cow, a 1980 winner of the American Book Award. Like Watership Down and Animal Farm, the novel is an allegorical fantasy which anthropomorphizes animals who must pit their good against evil, and like The Lord of the Rings, the book is grounded in medieval legend and myth.

The narrative begins after the conclusion of a terrible battle with evil in the form of the hideous, gigantic underground serpent named Wyrm. The lord and master of the animals who used to inhabit the Coop is Chaunticleer, Chaucer's commanding and unapproachable rooster with the coral comb, golden features and black beak. His virtuous and graceful lady is the hen Pertelote, and together they oversee an animal family of hens, mice, a weasel and one dying fox.

At the end of The Book of the Dun Cow, the noble dog Mundo Cani was killed when he dove into the abyss and punctured the eye of Wynn, blinding the serpent. Russel the Fox was also wounded in the battle, and his injury to his snout was a cruel one because the goodhearted fox was an incurable talker and so his snout would never heal. It is Russel's death and Chaunticleer's guilt at the sacrifice of Mundo Cani that drives the rooster from his position of leadership. But, eventually his compassion for the poor, crippled hen Chalcedony revives Chaunticleer and leads him to marshal the animals in a massive effort to horde food for the Fimbul Winter that comes too soon.

Of course, a final showdown between Chaunticleer and Wynn is inevitable. The rooster is led to the serpent's cave by a nervous coyote and a plain brown bird who sits outside the cave with her broken wings and a destroyed tongue that can only make the sounds "Jug, Jug" and "Tereu." The total commitment of Wyrm to evil leads the monster to conclude that the one true victory will come if he can enter the animals at the heart and have them choose evil for themselves. The novel's climax is convincing and frightening once the reader has accepted the animals as substitutes for humanity.

Walter Wangerin's success in writing in this unique form of the genre lies in his ability to give the animals believable human personas. Chaunticleer and Pertelote are lifted from The Nun's Priest's Tale and expanded to play the roles of a medieval knight and his lady. The foolish and easily-flattered rooster in Chaucer's tale is transformed into a viable tragic hero in Wangerin's story. The author is especially adept at granting dignity and warmth to smaller creatures. The Brothers Mice always believe in the possibility of healing. "Moreover, they had an absolute faith in pats on the back and smiles and nods and tiny salutes - and humor." But, by far the best creation is that of the frightened coyote named Ferric. For him life is a dangerous proposition, and he spends a great deal of time in a frozen position, staring at the danger his carefree wife Rachel ignores. "What Ferric had, he had a headache. He had a wife."

The Book of Sorrows is a fine book about the way evil enters the world, and this newly told story of Chaunticleer is one that details the loss of his innocence, of his love and of his God.

Once upon a prelapsarian literary time, the now puny wobbly world was the absolute, still center of a purposeful universe, where God walked the clouds and, in Chaucer's phrase, "Beestes and briddes koude speke and synge." Here animals are the keepers of the kingdom, their Coop the center of the world, their charge to guard Wyrm, the Evil One, the great globe-circling. God-hating serpent. It is the animals' banded peace, their bond of love that keeps Wyrm chained deep in the dark damp rotting bowels of the earth.

In this mythopoeic cosomology Walter Wangerin Jr. has set "The Book of Sorrows," the powerful, troubling conclusion to his award-winning 1978 "Book of the Dun Cow." That beast fable was loosely compared to zoomorphic tales as diverse as the satirical "Animal Farm" and the whimsical "Wind in the Willows." But, like J.R.R. Tolkien, Mr. Wangerin is a medievalist, and his techniques--his interlaced plot, his allegorized characters, his humor and the grand simplicity of his style--have more in common with medieval bestiaries and folk epics than do most modern fantasy adventures.

On the other hand, Mr. Wangerin is also a Protestant minister, and his purpose has more in common with Milton's than with those of either Chaucer (from whose comic homily "The Nun's Priest's Tale" come Mr. Wangerin's main characters, the proud rooster Chauntecleer and his lovely Pertelote) or the Irish epic the "Tain-Bo-Cuailnge" (from whose earliest manuscript, the "Book of the Dun Cow," comes his first title).

For in his two-volume fable, Mr. Wangerin is writing nothing less than a parable of the Fall, an attempt, if not to justify God's ways to man, then to ask God to do so Himself. His Wyrm is none other than the great dragon, "that old serpent, called the Devil, and Satan" of the Book of Revelation. "Goddamn that Serpent." The narrator cries early in "The Book of Sorrows." "No one had sinned enough to justify his presence in the universe. ... Mighty God, you talk to us! Tell us: why does Wyrm exist?" And "Why? Why?" is Chautecleer's elegiac refrain. The rooster was once God's troubadour, giving with his canonical crows direction and meaning to creation--but now he is God's accuser, tormented by the lonely burden of authority, by hubris, guilt and self-pitying despair.

In "Dun Cow." Wyrm's battle for freedom took shape as a war between his minion Cockatrice, with his basilisk offspring, and the animals, led by the warrior king Chauntecleer. Despite the loss of children and friends, despite doubt, Chauntecleer rallies the Keepers and defeats Cockatrice in heroic single combat: "I can choose against evil!"

But Wyrm still lives, and Wyrm is death, and the first book ends with the ominous rumble of a deadlier battle to come. For the greathearted dog Mundo Cant, the soul of love, loyalty and forgiveness, has sacrificed himself by leaping into the cracked roiling earth to blind the Serpent and is sealed beneath the Netherworld Scar. "The Book of Sorrows" opens there, in a gray funeral winter, with Chauntecleer grieving alone, sinful in his proud despair. Finally he comes to see his heroic destiny, his purification, as the quest to go down to hell and rescue the good he has despised in his contempt for the dog who saved his life. Like other epic heroes, his "righteousness ... is to fight and die," by killing the dragon to restore life to the wasteland. Until he can do so, he withdraws and broods, and the cold winter closes on his kingdom; wolves gather, chaos rattles near.

In the Underworld, Wyrm is waiting for the hero, but waiting in a guise designed to defeat heroism itself. For what if Perseus or Beowulf or St. George charged the dragon and found it a rotted corpse? What if there were no Hector for Achilles to challenge? Mr. Wangerin's remarkable revisioning of the epic climax of combat leads Chauntecleer to a different battleground from those other heroes', where triumph lies in his courage to accept the Dun Cow's final message, brought by the least of God's creatures, a cowardly coyote whose family Chauntecleer has slain.

Like its predecessor, with which it should be read, "The Book of Sorrows" is a profoundly imagined and beautifully stylized fable of the immemorial war between good and evil; the battlefield is never really Grendel's den or the Blatant Beast's cave but the heart's breast, in which, victorious. Chauntecleer stabs himself to kill the Wyrm breeding there. "The Book of the Dun Cow" was called a children's book. If so, we are all children, asking, "Why?"