By Peter Matthiessen

Random House. 392 pp. $21.95

"IT WASN'T justice they were after, but a good night's sleep."

Peter Matthiessen's seventh work of prose fiction is a nightmare of a novel, intricately structured, richly documented, utterly convincing; one which is certain to linger in the memory like an experience we have lived through but cannot, for all our effort at analysis, comprehend. Like other works by this distinguished American writer it is clearly an enterprise of obsession: in this case, a moral parable in the guise of a historical account of Edward J. Watson, "Mister" Watson as he was called, the "most notorious figure in the history of southeastern Florida."

Born in 1855 in South Carolina, a prosperous sugar-cane farmer in the Everglades in the 1900s, "Mister" Edward Watson died in 1910 in a spectacular fashion that soon passed into legend -- he was gunned down by 20 of his neighbors in the remote island-community of Chokoloskee. (Days after the fact, the men were hastily deputized by the county sheriff so that the murder, committed by a "posse" and not a vigilante gang, was legal.) In Matthiessen's chronicle -- a sequence of linked testimonies by associates of Watson and eye-witnesses to the killing -- the near-mythic Watson emerges as mercurial, unpredictable, a figure of contradictions: a "good family man" who is also, upon occasion, a cold-blooded murderer; a sociopath-drunk who is also a "generous" neighbor and host; a "borned politician" who is also a cynic operating under the secret, sinister wisdom that "Nothing mattered." Like the then governor of Florida, Watson has a dream of draining the Everglades in the name of "progress" (which is to say "profit" -- for him). He is a common bully, yet, to ordinary, easily cowed men, a kind of hero; charismatic, admired -- even by the men who finally, and somewhat belatedly, gun him down, emptying, in a frenzy, their shotguns and rifles into his body. By the end of this complex narrative, Watson has beome an emblem of evil: the figure who is a nightmare to society not because he is outwardly despicable but because he is so charming.

The author spent six years researching his subject, reading in old newspapers and books and interviewing Floridians who were descendants of Watson and those who knew him. "I discovered . . .. that the 'true story' of someone about whom so much has been said and written is as elusive as the 'true story' of a man about whom almost nothing has been verified." Killing Mister Watson is, of course, finally a work of the imagination; Matthiessen does not disarm criticism by labeling it a nonfiction novel -- that most dubious of literary terms. Its novel-prototype is perhaps Faulkner's masterpiece, Absalom, Absalom!, in which the shadowy, enigmatic and doomed Thomas Sutpen lives out the passion of his grand "Design"; like Sutpen, Watson is revealed solely by others' accounts -- we are never brought into his consciousness, never allowed to know him intimately. And since accounts of the man differ so radically, we are left, like the detective-historian, with more questions than answers, and with a sense of frustration. The more we learn about Watson, this "accursed" figure, the less we seem to know.

Peter Matthiessen's exemplary body of work -- which ranges from the poetic, elliptical novel Far Tortuga to the vividly written and haunting travel-memoir The Snow Leopard (winner of a National Book Award), from the polemics of In the Spirit of Crazy Horse (which embroiled the author and his publishers in a protracted libel suit, ultimately dismissed) to the sophisticated fictions of On The River Styx -- is informed by a moral intelligence that keeps indignation, even outrage over mankind's folly, in scrupulous writerly control. Matthiessen's strategy is to focus upon representative men ("men" is employed here deliberately -- Matthiessen's female characters are less forcefully drawn); he is less interested in the psychology of the individual than in the psychology of social groups, particularly those, like the Everglades settlers of Killing Mister Watson, who find themselves in situations of unsought and unavoidable strain. Matthiessen is a cultural analyst in the most fundamental sense -- the subject of his scrutiny is the human bond, the precariousness of what we call community; the mysterious genesis of "morality" itself.

Killing Mister Watson is a disturbing work because its paradoxes are not resolved. Unlike, for instance, a genre mystery, it does not "solve" its murders. Evidence seems irrefutable that Watson has killed a number of people, often by shooting them in the back (including a woman nine months pregnant); yet, like the confused and demoralized residents of Chokoloskee, the reader is denied certainty: Watson remains distant, opaque, secret.

The structural effect of the many interlocked testimonies gives the novel a braided texture. The narrative line of tension is many times advanced, dropped, reiterated, advanced again, dropped, even refuted, so that the novel's power is accumulative, rather than constant. The end -- the slaughter of Watson -- is also the beginning, but, this second time, when Watson's wife cries, "Oh God! They are killing Mister Watson!" we not only know why these 20 "ordinary" men are killing the object of their communal awe and terror, but we have become virtual participants in their frontier vigilante justice.

Asked by Watson's daughter whether the act was in fact justice or murder, the sheriff, an ineffectual but well-intentioned man, says, "This was murder, yes. But I reckon maybe this was justice too." If the author speaks through any voice, it is likely to be this voice. Yet questions remain. How do we recognize evil if no one will call it by its name; how do we exorcise it, when there is no legal "proof" of its existence? How, in effect, do we acquire civilization? And how, given the precarious nature of man, do we retain it? Killing Mister Watson is a considerable achievement -- its creator's obsessions become our own, perhaps irremediably. Joyce Carol Oates is the author, most recently, of the novel "Because it is Bitter and Because it is My Heart." She is the winner of the 1990 Rea award for the short story.