Who Did It? : Tale that deliberately leaves loose ends is at once fascinating and frustrating : THE BLUE AFTERNOON, <i> By William Boyd (Alfred A. Knopf: $23; 373 pp.)</i>

If you write a book and call it “The Unsatisfying Mystery” and it turns out to be an unsatisfying mystery, have you succeeded or failed?

Certainly, William Boyd is up-front about it. The narrator of his clever and exasperating novel protests from time to time at the richly configured story of passion, intrigue and murder told to her by Dr. Salvador Carriscant, who turns up when she is divorced and in her 30s, tells her he is her father, and enlists her on a quest.

Here, after 350 pages and at what ought to be the novel’s winding-up and tying-together, she is still complaining:

“In many ways Carriscant had been as honest and as unsparing as anyone I could imagine. He seemed to have held nothing back, providing me with details and intimacies I would never have asked for myself. But in the end it was his story and he was free to emphasize and ignore what he wished, to select and choose, shape and redirect. . . .”

Her objection may be the reader’s. Boyd has not written “The Blue Afternoon” in such a way as to signal it as one of those post-modern puzzles whose point is not the mystery but the self-conscious act of telling a mystery. Set in the Philippines at the turn of the century, it is presented, for the most part, as the kind of sumptuously assured and detailed narration that gets recounted in tranquillity, years later.

True, there suspicious oddities. For one thing, the framing passages--those where, in an Edwardian novel, someone plonks himself down in an armchair, lights a cigar, and regales his fellow club-members with a story about the untamed horrors of a comfortably distant world--are 100 pages long and jittery.

The person who retails Carriscant’s story to us, and carps at it, is a Los Angeles architect named Kay Fischer; their encounter takes place in the 1930s. She is oddly uneven herself. At the time her father appears, her brilliant modernist ideas had been stolen by her former partner, who arranged, furthermore, to have a spectacular Le Corbusier-style house she built bought up and demolished.

There is a hint of the paranoid here; there is also Kay’s odd availability--at once unquestioning and skeptical--to the old man who turns up, claims paternity and takes her off to Europe to help him find a woman he had loved and lost 30 years before. If the story Carriscant tells on the ocean crossing to Lisbon arouses her suspicions and frustrates us, we are not all that sure about her, either. What if Conrad’s Marlow were ejected from his club for non-payment of dues just as he was about to begin “Heart of Darkness,” or Sherlock Holmes’ Dr. Watson were disbarred for a phony medical degree, or Black Beauty were revealed to be a mule?

Such fidgety uneasinesses contrast with the apparently assured and utterly engrossing story that Carriscant has to tell. Boyd, the elegantly unpredictable author of “A Good Man in Africa” and “Brazzaville Beach,” writes rather as people wrote 70 or 80 years ago, though with modern and graphic irruptions. It is pastiche and just about irresistible. That is, we cannot resist it; only, at times and signaling obscurely, it seems to resist us.

The son of a Scottish engineer and a local landowner’s daughter, Carriscant returns from Edinburgh to Manila in 1902 to practice surgery. The United States had seized the Philippines from Spain, and had subsequently waged a bloody war against Philippine nationalists. The fighting is mostly over by the time Carriscant arrives, but the spilled blood--4,000 dead Americans and, by Boyd’s choice among widely varying figures, 200,000 dead Filipinos--haunts the story and gives it a feverish extravagance.

Written in brief, pulsing chapters, the account consists of four simultaneous and interrelated stories. One is the savage rivalry between Carriscant, who introduces modern surgical practices into the Philippines, and Cruz, his hospital’s arrogantly old-fashioned director. Another is the impassioned, ultimately fatal effort of Carriscant’s trusted anesthetist and close friend, Pantaleon Quiroga, to build the world’s first successful flying machine. A third is three murders, two of soldiers and one of a civilian woman, pursued with grim energy by the American police chief, Paton Bobby. And finally there is Carriscant’s love affair with Delphine Sieverance, the wife of an American colonel.

All four are told with a brilliant, near-hysterical clarity. The portrait of Cruz, who operates in a blood and pus-stained frock-coat, disdains clean gowns and asepsis, and derides Carriscant for washing his hands before operating--the time to wash, he insists, is afterward--is vivid and chilling. In his hatred for modern methods, for his modern rival, for Americans and American ways, he represents, as well, the bitterness of the displaced Spanish classes.

Pantaleon, is much more complex and winning. He loves Carriscant, is torn--as the Philippines was--between welcoming an American era that meant modernity and an end to Spanish rule, and horror over the violent and implacable U.S. Army repression. The beautiful, frail flying machine he builds, and with which he hopes to win an international prize, symbolizes an idealist’s flight out of history’s horror.

Cruz and Pantaleon become entangled in Bobby’s fierce and blundering investigations of what may be terrorist killings. Carriscant, though he is friendly with Bobby and helps him, will himself fall victim to the investigation, and will serve 16 years in prison. His arrest, after Col. Sieverance is found mysteriously murdered, curtails his plans to flee to Europe with Delphine Sieverance. They will not see each other again until he and Kay find her, dying, for a brief and touching reunion in Lisbon.

Their affair is the book’s lovely and arousing heart. It is precarious and terribly dangerous: their rendezvous take place on Carriscant’s examination table and, later, in the barn where Pantaleon is building his airplane. They step over propellers and engine parts to get to his camp cot. Two sorts of flight; Boyd juxtaposes them brilliantly. And he portrays sexual passion, something much rarer in contemporary writing than sex itself.

Had Boyd written Carriscant’s four-strand narrative less vividly, had he made it entangle us less, perhaps the deliberate holes he leaves in it would matter less. We are poised to have the mysteries solved: who killed the soldiers and Col. Sieverance, what was Paton Bobby really up to, how much of the truth is Carriscant telling Kay, how much truth is Kay telling us?

We end with contradictions, inexplicable actions and loose ends. They are deliberate, of course. Boyd, I believe, has set out to write a book about life, death and narrative itself, as just that: loose ends. His trouble is that he has written too well. He has constructed too beautifully to be able effectively to de-construct. He has not blown up his story, he has pitted it and scratched it.