IT IS HARDLY STARTLING to come across a novel about two teen-agers taking a joyride on a stolen motorcycle, even when the story is told with exceptional perception and understanding. Such journeys have been taken before. The joyride in this case, however, is from Bangkok through Cambodia and in the direction of Saigon, in 1969. Gordon Chaplin has been there -- he reported from Southeast Asia for Newsweek -- and he renders the landscape with clarity and precision. What is especially gratifying about this novel, however, is the way it delineates the barren, amorphous, and treacherous landscape of adolescence, and the attempts of two boys to escape it.

Jimmie Dee is the son of an Army colonel who has recently died. The novel stays mostly within the present -- we catch glimpses of the past only through skillfully interspersed flashbacks -- but in the little we see of Jimmie Dee's father he seems a strong and demanding authority figure, a formidable opponent in an oedipal struggle. The novel's narrator, on the other hand, identified only as Jones (a name Jimmie Dee gives him) has parents who almost don't exist at all; his father is the head of the Peace Corps in Thailand and his mother an ineffectual woman who keeps parrots. The novel seems intentionally vague on these points, as if to concentrate on the present and suggest the universality of the boys' struggle.

However peculiar their circumstances, these seem to be boys we have met before. Jimmie Dee is intense and unpredictable, the more violent, energetic, and decisive of the two. He seems to be grappling with a specific incident -- his father's death -- and with the fact of death itself. He wants to take the joyride because reality has overwhelmed him, seems to be pressing in on all sides. Jones, on the other hand, cannot find enough reality. He is suffering from the Bangkok Lazies, in which the world seems so unreal as to be paper thin. He is bored and apathetic, feels worthless, and wants to find a place where things seem real, however terrible that reality may prove to be. At the suggestion of Jimmie Dee, he decides to check out Saigon.

Jones, of course, is the kind of adolescent narrator who says much more than he knows he is saying. He is at that difficult point in life where he has a man's energies -- especially sexual energies -- and nothing to focus them on. He and Jimmie Dee have talked about sex, acted knowing about it, but neither one is experienced. There are suggestions, however, that Jones is beginning to understand the strong erotic attraction that he feels for Jimmie Dee. He sometimes sees Jimmie Dee as his mirror image, and in a sense he is -- that frantic obsession with death is the flip side of an overwhelming ennui -- but he is also an image of Jones' burgeoning manhood. Jones puts off the erotic attraction, but we have the feeling he would accept it if given half a chance. Jimmie Dee, however, won't hear of it. Halfway along in their journey, they meet a young woman who has a magic act in a nightclub. She allows the boys to stay with her, seems on the verge of seducing Jones; instead she gives them the opportunity to accept the attraction they have for one another. They refuse, and, as if they have refused their fate, their bad luck begins.

It is unfair in discussing this kind of adventure novel to reveal much of the action. Most of it takes place in the exotic landscape of Cambodia, and the question, as the boys waver and falter, is whether they will make it to Saigon at all. Government men try to shield and stop them; they meet tourists who disgust them with their superficiality and a deserter who seems flat-out crazy. Eventually the action comes to seem almost symbolic -- there are omens, rescues -- as if the boys represent, if not Everyman, at least every adolescent. Eventually, too, it is Jones who becomes the more determined partner, as the boys' personalities begin to merge. The action finally climaxes at the home of an American soldier of fortune named Stockton, the one worthwhile male they have come across.

It is only in a few moments toward the end that the novel's power somewhat diminishes for me. Stockton seems a stock character, with his mysterious past, his houseful of curiosities, his broad wealth of experience, and a speech he makes at the end to Jones -- however wise -- seems rather pat. What happens to Jones and Jimmie Dee at the end also seems too pat, as if they have finally become symbols and must live out their symbolic fate. I even felt that the novel in places might be suggesting that America became involved in Vietnam because the country, like Jones, was spoiled, bored, and hungry for reality. That would be too large a theme for this rather small novel.

At his best, however, Gordon Chaplin is a powerful storyteller. Through much of the book the boys' experience is crazy and doesn't quite add up, just like life, and Jones' adolescent voice remains authentic even while telling its story in rich and precise detail. Much fiction about adolescence takes up experience that is typical, as if finding common ground where we can all sympathize. Gordon Chaplin shows us that, even in experience that is wildly exceptional, a good novelist can enable us to see ourselves.