BOOK REVIEW : Two Ripe Subjects: Hollywood, Marriage : THE DIAMOND LANE <i> by Karen Karbo</i> , G.P. Putnam’s Sons $19.95, 320 pages

Since so much of Karen Karbo’s second novel deals with the topic of marriage, which Voltaire once called “the only adventure open to the cowardly,” the title, “The Diamond Lane,” has a nice double meaning.

The diamond lane, as every freeway commuter knows, is the corridor reserved for cars containing more than one person. It’s the one place in the world where it’s against the law to be single.

Actually, this astringent, humorous novel tackles two subjects ripe for satire--the Hollywood movie industry and marriage--both notoriously fickle institutions requiring blind hope to sustain life.

In the film business, people spend 90% of their time hoping for the deal, the option, the big break, even a lunch meeting. In marriage, about the same amount of energy is devoted to hoping for intimacy, longevity and happiness. “It’s psychological work, having hope,” as one character in this novel says. This is something the FitzHenry sisters understand very well. They just hope for very different things.

Mouse and Mimi FitzHenry, two sisters originally from the San Fernando Valley who are now in their mid-30s, couldn’t be more different.

Mouse, whose real name is Frances, is a no-nonsense documentary filmmaker who has lived in Africa for many years. She’s one of those women for whom clothes and makeup are inconsequential. She and her English boyfriend, Tony, are willing to go unwashed for weeks and live on handouts in order to turn out unsalable documentaries on tribal marriage customs.

Mimi, on the other hand, is a creature of Hollywood, an aspiring actress and screenwriter who toils away as a lowly secretary in a production office, a woman obsessed with her appearance and weight, willing to accept the crumbs of attention tossed her way by the obtuse and whining Ralph, her married lover, another would-be screenwriter whose latest script is “Girls on Gaza.”

Mouse and Mimi are reunited when Mouse is summoned home by a family medical emergency (her mother, Shirl, is clobbered by a ceiling fan in a restaurant). In Los Angeles, Mouse finds herself yielding to pressure from her ailing mother to marry Tony, who has returned with her only to immediately succumb to the make-a-megabuck syndrome.

As if the prospect of Tony’s sellout and the upcoming marriage weren’t disconcerting enough, Mouse discovers a Los Angeles of new and unfathomable oddities has sprung up in her absence: “The mysteries of life had multiplied like mold in a bag of cheap hamburger buns during a heat wave.”

The marriage of Mouse and Tony turns into a farce when Shirl, who has received a handsome insurance settlement from the ceiling fan accident, turns over a hundred thousand dollars in order to stage the wedding of the century, and Ivan, a seedy but talented documentary maker who is Mouse’s ex-boyfriend as well as Mimi’s ex-husband, turns up and persuades Mouse to let him film the preparations for the big event, much to Tony’s displeasure.

Part of what Karbo is satirizing in this novel, in an often very wicked fashion, is the way the ordinary rituals and activities in life--love, work, marriage--get twisted into the most bizarre shapes when money and Hollywood values enter the picture.

Modern, urban, upwardly mobile American life--especially as played out in a myth-making centers such as Los Angeles--is really Karbo’s subject. She understands the banalities and excesses, the contradictions and absurdities of living in a place where knowing not to put glitter in your stucco is construed as good taste.

“The Diamond Lane” is meant to be a comedy, and it is laugh-out-loud funny in places, but it’s almost too clever for its own good. It’s easy to laugh, for instance, at Mimi, to respond to her ditzy barbs about show business, but when she’s retching, purging herself after a cookie binge, things turn quite uncomfortably serious. How funny can a bulimic really be?

Karbo sustains her tale by contrasting misery and humor, real filmmaking (real documentary) and the crass commercial product, poor humble Africa and fat, gluttonous America. The difference between characters and their worlds are meant to anchor the novel. One of the difficulties is that Hollywood is such a hackneyed subject. Africa, however, isn’t, and in the passages dealing with Mouse’s life there, Karbo’s writing really soars.

Mouse has the kind of moral center necessary to add weight to this kind of satire, and when the story centers on her, it takes on depth and not only reveals the narrative talents of the author, but also allows her strongest ideas to emerge.

Next: Carolyn See reviews “The Revolution of Little Girls” by Blanche McCrary Boyd (Alfred A. Knopf).