O PARADISO<i> by Conrad Osborne (Arbor House/William Morrow: $18.95; 339 pp.) </i>

To an outsider, the arcane inside world of any business is mysterious and exotic. Obviously Conrad Osborne is thrilled by the imagined excitements backstage at the opera, or he would not have chosen a fringe performance of Meyerbeer’s “L’Africaine” as the basis for his novel, “O Paradiso.” Meyerbeer’s opera has as its climax Vasco da Gama’s famous aria “O Paradis,” since the opera was, of course, written in French.

The potentially amusing idea of a fringe opera company in New York run by a retired opera diva, trying to mount this monster on a shoestring in a leaky movie theater misfires if only because Osborne doesn’t tell us enough about the performance. At the actual premiere in the final chapter, we read about the traffic jams, the peculiarly exotic audience, exotic since the singer singing Selika is a famous black cabaret star, the crush at the bar, the rain coming through the roof, the orchestral rail collapsing, a front curtain that doesn’t mask, but hardly a word about the performance. This is, to say the least, a letdown. We learn most about the performance from Gerald Borden’s review. I like particularly his reference to having seen “the first of two threatened performances.”

Borden, who has also written the program notes, is an old music coach of the diva and president of a particularly argumentative record club that specializes in the collection of historic, and, especially, pirated recordings. The violent attempts of this club and its warring members to determine the eventual possession of a collection owned by their deceased president, forms a bewildering subplot. In the violence, the club’s regular operator of the pirate recording machine, the Nagra, is incapacitated, and his dim replacement has to have, in his coat, ballast on the side opposite the Nagra so as not to be “a lopsided pirate.” Borden’s relevance to the plot and the performance of “L’Africaine” is faint, but his is a recognizable character and in a prissy way rather endearing. On several occasions, he resorts to a childhood habit of crawling on all fours to avoid being seen.

Kurt Oberhausen, the other protagonist, is far too much larger than life. . . . The tenor’s singing teacher, his connection with “L’Africaine” is even more tenuous. He is an ex-baritone himself who is portrayed far too fiercely as the roaring boy, fulminating about Jews, blacks, Latinos and gays. His attempts to keep drinking throughout the performance are, however, genuinely funny.

I suppose the core of the book is the separate attempts by Borden and Oberhausen to discover a new or lost happiness (Paradise). They do not meet until the end of the book and then only fleetingly. But the most moving and gripping chapters are those dealing with Oberhausen’s visit to Colorado to see his pregnant daughter, Linda, and Borden’s return to his hometown in Upstate New York (where his father used to be minister) and his chance encounter there with an old gay friend. In both cases, the writing gains a new dimension-- Oberhausen’s sad, half-drunken, reverie at the Boulder party and Borden’s attempts to rescue Maynard not only from an actual ditch, but from his decision to turn his face against the world.

The book is maddeningly overemphatic. Jolly sex romps, drink, drugs, travelogues, jagged English, the description of the auditions reads more like a particularly violent episode in Tom Wolfe’s “The Bonfire of the Vanities.” Osborne describes an opera director beginning the first rehearsal thus: “He takes a slow drag on the cigarette, but in the middle of the exhalation breaks into the rhythm with a sharp exclamation, ‘Meyerbeer!’ He changes tempo again, slowing and breaking each word to distinct syllables, his tone implying some secret about to be probed. ‘Gia-co-mo Meyerbeer.’ ”

“L’Africaine” has just opened at the San Francisco Opera with Placido Domingo in the role of Vasco da Gama. This book is by no means required reading, but you might nonetheless enjoy it on the way there.