No Heroes in Ulsterworld : THE WILD COLONIAL BOY <i> by James Hynes (Atheneum: $18.95; 356 pp.) </i>

Jimmy Coogan, renegade battalion commander of the Irish Republican Army, is the first person we meet in James Hynes’ exciting and very well written first novel, a tightly-wound chronicle of the continuing troubles in contemporary Ireland.

Coogan, a 15-year veteran of guerrilla warfare, is a Provo leader without any men, following a shoot-out three months ago between his unit and a “suspiciously lucky” British patrol. Furious with the IRA chief of staff he thinks is about to sell out the movement by taking a seat in Parliament, Coogan is planning an unauthorized terrorist strike, “something spectacular” in England to spoil the chances of any politician’s compromise.

Driving alone past the flinty farms and open moorland north of Belfast, with ten pounds of Czech plastic explosives stuffed in an Adidas carryall, Jimmy Coogan is an outraged banner headline waiting to happen.

But Coogan needs help. Sought by the Provos and shunned by the locals, his only ally is Maire Donovan, the Sinn Fein city councilor for West Belfast to whom he is secretly married. An outspoken public figure, Maire is in no position to participate in her husband’s scheme to get the explosives into the sympathetic hands of the London Brigade. The wanted Coogan dare not try to carry the plastique into England himself. Where is the unknown innocent Coogan can use as an accomplice?

Enter Brian Donovan, Maire’s American cousin. Amiable, at loose ends, coasting on charm and good intentions, young Donovan has been deputized at the last moment to bring his dying grandfather’s $10,000 from Detroit to Ulster and the Provos’ pension fund. To Jimmy Coogan, Brian sounds the perfect choice to tote explosives past border guards.

Maire is not so sure. “Americans are like children,” she tells Coogan. “They come here like tourists to see a bit of aggro, get their thrill, and go home. It’s like . . . Disneyland to them. Ulsterworld.” When she encounters her cousin, he is even more unsuitable than she’d feared, seeming “less a foreigner than someone from another planet entirely.”

Still, she arranges for Brian and Coogan to meet. Coogan sugarcoats his request with reassuring falsehoods. The apolitical American, following momentum and impulse, is drawn in.

There are no real heroes in this taut thriller. Nearly everyone’s actions are compromised by obsession, ambition or willful ignorance. Coogan is not averse to causing a bloody IRA schism to turn things the way he wants. Joe Brody, the seeming moderate Coogan is opposed to, shops his enemies to “trigger-happy” British troops.

Maire Donovan is caught between her husband’s plotting and her own better judgment, and the incriminating Polaroid she takes of her cousin to insure his loyalty eventually causes all kinds of grief. Brian’s fumbling efforts to do the right thing are spoiled by his failure to confront hard realities; his less-than-complete honesty with Clare, a sweet and even more innocent American abroad, leads them both to the edge of disaster.

Brian at least means well. Much more distasteful are the ethical twists and turns made by Tim McGuire, the obese free-lance journalist Coogan bullies into assisting him. “Here he had the story of a lifetime,” McGuire reflects after Coogan lets him in on his discontent, “and he couldn’t print it. . . . He believed in the Republican movement . . . and if he printed what Jimmy Coogan had just told him, he’d be siding with those who wanted to bring it down . . . “ Besides, McGuire asks himself, what if Coogan fails and Brody wins? “Then I’d be out in the cold forever, he thought, reviled as Jimmy Coogan’s publicist, the end of my career in the North . . . “ Better all the way around to betray Coogan, McGuire decides.

If Hynes offers no unequivocal good guys, what he does deliver is a terrific read, filled with believable and memorable characters who are as dimensional and full of surprises as the folks you meet in real life. They charm, they startle, and often they make you laugh.

The tension that builds throughout the book is leavened by wry humor, with Maire seeming to have the best lines. (She also gets perhaps the most powerful scene in the novel, an unexpected and flesh-chilling Gaelic wail of grief.)

With this impressive debut, novelist Hynes stakes a fair claim to part of that morally complex modern political terrain mapped out by the likes of Graham Greene, Joseph Conrad and Robert Stone. His characters meet fates that seem appropriate and even inevitable, while the larger issues remain realistically unresolved.

A brief exchange occuring halfway through the book seems emblematic of a struggle that seems to know no end.

“Are we winning, Joe?” an old Belfast Brigade vet asks Joe Brody.

“No,” Brody answers, “but we’re not losing either.”

“Oh, aye,” the old man concludes, “that’ll have to do for now.”