NO MERCY: A Journey to the Heart of the Congo.<i> By Redmond O’Hanlon</i> .<i> Alfred A. Knopf: 462 pp., $27.50</i>

Not all that long ago, in what was still a pre-mass travel age, travel writing at its best was marked by an urbane, if impersonal, regard for cultural and societal demarcations. Whether crossing the empty quarter in Arabia or exploring the upper reaches of the Amazon, the writers never thought to mistrust their Western role, authority or ability to understand a thinking often so different from their own. As quasi-cultural emissaries on a mission to retrieve and preserve a foreign past, they largely held back the personal out of a need to conform to convention, as well as out of a fear that the use of the private and intimate might impair their judgment. Not so the present-day crop of writers--many influenced by Ryszard Kapuscinski and the late Bruce Chatwin--who have come to reject an often luminous style in favor of a discordant rawness and substituted the role of civilized go-between for a powerful if occasionally disconcerting in-your-face eclecticism, in which the author’s personal life is a revealing factor. The gregarious, self-questioning, self-disparaging Redmond O’Hanlon bears all the earmarks of this group.

His title, “No Mercy,” is telling. Classic O’Hanlon, it goes to the core of what is a self-punishing book. O’Hanlon, the indefatigable traveler whose insatiable curiosity impels him to seek out the unknown, the inaccessible, the downright hazardous, is at it again, but by now, on this, his third trip, isn’t it time to ask, what is it about the jungle? In “Into the Heart of Borneo” (1985), he recounts his and the poet James Fenton’s stay among the headhunters in Borneo; on his next trip “In Trouble Again” (1989), accompanied by a tough, street-wise former manager of a casino, O’Hanlon headed for the Amazon rain forest to look for the ferocious Yanomami. Now, his English cheerfulness undiminished, he has traveled to the Congo, ostensibly in search of the ancient creatures that might yet exist in the vast seemingly changeless primeval jungle in the north. This time a well-meaning American biologist, Lary Shaffer, fulfills the exacting role of sidekick and sounding board. Their chummy, often heated discussions on everything under the sun highlight O’Hanlon’s disarming candor and, as alluded to by Shaffer’s tart comment: “First off--you’d turn everyone’s problems into jokes, to protect yourself,” reveal under rambunctious good cheer an equivocal, even guarded, disposition.

In Brazzaville, O’Hanlon and Shaffer first meet with Marcellin Agnagna, a smooth, ambitious biologist trained in Cuba, who is to accompany them to the remote Lake Tele area where, on his prior visit in 1982, he claims to have sighted a sauropod dinosaur in the water by the shore. Many ventures are based on far slimmer evidence.

The precautionary visit by O’Hanlon and Shaffer to a fetisheuse, a kind of African interpreter of messages from the world of the spirits, sets the tone for the expedition. O’Hanlon is determined not to provoke the gods or, for that matter, the ire of the Pygmies they’ll encounter, to whom the Mokele-mbembe, the only surviving descendant of the ancient dinosaur, is a near-mythical beast, something to be imagined, revered and feared.

“Then tell me--what is it you really want?” the perspicacious fetisheuse says to O’Hanlon, as if intuiting his ambivalence and skepticism. “You don’t speak your desires. You think them.” Then, intuitively, she singles out Shaffer, warning him that he’ll not survive if he stays a day more than two months in the primeval forest of that region.

With Agnagna and his two bumbling African assistants on the team, they now are, at least on paper, an official expedition. The steamer that will take them upriver as far as Impfondo has in tow dozens of barges on which hundreds of villagers are encamped. “They will sleep in the open for two weeks, maybe three. Some of them will die. One or two of the very young children will roll over in their sleep and disappear down the gaps into the river. It always happens.” Agnagna’s matter-of-fact description, a sobering introduction to the Congo, is made all the more emphatic when O’Hanlon, idly scanning the river through his binoculars, spots a young boatman, nearly drowning, as he is being swept away by the powerful current. O’Hanlon yells out to Agnagna to alert the captain. Agnagna rebukes him: “If you make a fuss like that every time someone dies, my friend, you won’t last. You’d be wasting my time. We won’t complete our mission.”

As one might expect, the mission yields incongruities. There is the spear-carrying chief with red paint on his forehead, his baggy loincloth embroidered with red, yellow and blue-green flowers on the patch over his genitals and Adidas running shoes on his feet. There is Shaffer ensconced in the jungle reading Dickens. Shaffer, with great dedication, is the dispenser of medicine--Floxapen and quinine pills for malaria, Amoxil for gonorrhea--while O’Hanlon is the paymaster, a walking cash machine who dutifully takes care of the tributes and other incidentals. With a bookkeeper’s eye, O’Hanlon details the petty disagreements; the roaches, bedbugs, ants, mosquito bites, ailments and remedies; the varied menu of sardines, bits of antelope, catfish soup, manioc and fou-fou; the frequent bouts of diarrhea and the daily sexual to-do of Agnagna and his two assistants as they scout for partners for the night. O’Hanlon, whenever the opportunity presents itself, shamelessly peeks into Agnagna’s diary, an unheard-of admission for an English gentleman. One day upon reading Agnagna’s underlined comment, “Setting out into the forest is like a soldier going to war. The return is never certain,” O’Hanlon contrasts his own exuberance and sense of self-discovery.

Everywhere they go, in the villages, deep in the jungle, O’Hanlon meets with African proscriptions, African warnings mediated by an African logic. People are never divorced from the power of the fetish, the power of the unseen. The living can survive only by taking the dead into consideration. No one finds the story about the Pygmy who changed himself into an elephant the least amusing or thinks to question Agnagna’s nephew when he remarks with a straight face that overnight his grandfather used to transform himself into a leopard in order to provide food for his family.

The idiosyncratic characters they encounter are straight out of Conrad’s fiction: a crocodile dealer in Mossaka, who casually informs them that cholera and sleeping sickness are back in force; a French monk, who keeps a Kongo nail fetish in his room in the belief that “one must get to know the enemy!”; a retired Brazzaville postman, who wants the French to return; an American pastor, Sandy Thomas, and his wife, who are conscientiously treating the Pygmies for TB, leprosy, yaws, cholera--diseases that have made their comeback since the departure of the French.

O’Hanlon, seldom at a loss for words, is oddly reticent about Shaffer’s abrupt mid-journey departure. Did Shaffer finally take the fetisheuse’s warning to heart? Or was there a sudden falling out? As a farewell gesture, Shaffer has O’Hanlon sign the note he has written: “I, Redmond, declare that I am going to the Lake Tele deathtrip of my own free will and hereby forgive [Shaffer] his escape.”

In a village near Lake Tele, an old hunter regales O’Hanlon with a story about the origin of life. “The origin of life reposes in a symbol whose name is Bolo. This symbol endows certain people with a power, a power which is generally transmitted through dreams.” Agnagna is quick to point out that the word bolo means vagina in Lingala.

By now it’s clear that O’Hanlon’s stated goal, the quest for the dinosaur and the entire high-risk adventure, is subordinated to a greater if unnamed pursuit. With Shaffer, his Western alter-ego, gone and distraught by the inconclusive outcome of his quest thus far, O’Hanlon, in what is a decisive turning point, proposes to Agnagna that they proceed farther north to Mboua. “How about it? A month? Two months? . . . “ Agnagna is aghast, “I’ve seen it before. White men like you--something happens out there in the forest. Every time. They get a kind of madness in there. They can’t leave. They never want to come out.”

As if to prove Agnagna’s assumption correct, O’Hanlon adopts a baby gorilla, spoon-feeding and caressing it. For the first time, he is emotionally unconstrained. He croons: “Five million years ago, you and I shared the same ancestors, the same parents, and you could have been my kid brother, and we could have held hands for real.” More than once he is told by Agnagna and the others: “You look disgusting--and you stink.” Indeed, in caring for the gorilla, he has begun to neglect himself. What’s going on?

Even though O’Hanlon accepts the African taboos as readily as he does the African logic of his companions and comes to rely upon his fetish, consisting of a small bundle of fur, bones and string, as much as they rely upon theirs, he goes out of his way--is it an act of empathy?--to experience discomfort, to wallow in the mud and to revel in the punishment he absorbs.

Why this need to cast doubt on the mission and his role in it? Will O’Hanlon’s drive for a revelatory ending stop at nothing? Does he wish to convey that in undertaking a journey such as this, one has to temporarily suspend one’s Western scruples and distrust and, above all, one’s Western reasoning? Or is O’Hanlon having a nervous breakdown?

In the end, it’s not the mysterious Congo with its many perils nor the often contrary Africans he encounters that matter, it’s O’Hanlon himself. The question, “[Am] I in your dream and are you in mine?” asked of O’Hanlon during a hallucinatory night visitation by the sinister and fearful phantasm Samale, might be addressed to the reader, for there is no gainsaying the power and riveting imagination of O’Hanlon’s turbulent dream, a dream from which he has happily emerged unscathed, time after time after time.