Michael Crichton is a novelist with a monkey on his back. The heroine his ingenious adventure story, "congo, is a gorilla, an ingenue named Amy who has a vocabulary of 620 words and the physical/psychological development of a 16-year-old human. Filled with adolescent yearning and condescension (she calls other gorillas "stupid"), the irrestible prima donna is fussy right down to selecting the color of her sweater during the winter.

Her trainer and kindred spirit is Peter Elliot, a scientist who fantasizes about discovering a new species which he would call, appropriately enough, "gorilla elliotnsis." Amy agrees to follow him to her native Africa because quite simply, like Juliet and Adele H., she is a woman in love.

The expedition to Zaire is financed by Earth Resources Technology Services (ERTS), a highly sophisticated data collecting company, to search for the big prize: a mother lode of industrial blue diamonds -- type IIb boroncoated -- which when developed would render nuclear energy and weapons obsolete. At the helm is 24-year-old Karen Ross, a luscious and immoral prodigy who has found professional fame with her treatise "Topological Prediction in n-Space." One of the most cynically written female characters in recent popular fiction, Ross dispenses vitamin pills and orders in not-so-equal amounts of generosity and self-interest, and she wins over the suspicious Amy only when Ross lets the teen-age gorilla play with her lipstick.

The main stumbling block to locating the diamonds as other explores have found, is a collection of killer gorillas who for some reason protect the lost city of Zinj located deep in the jungle. (The legendary Zinj is also the basis of H. Rider Haggard's novel "king Solomon's Mines.") The gray gorillas -- the African equivalent of Bigfoot -- are armed with stone slabs which are used to crush visitors' skulls in some form of primitive ping-pong. It is hoped that Amy will be able to communicate with the gorillas and translate, through signing, for her human friends.

Rounding out the expedition is Captain Charles Monro, a bush guide and gun runner, who found an unsavory reputation as a white mercenary under Col. "mad Mike" Hoare. Ross enlists him for as many cold-blooded shortcuts as possible. With the group teamed only for expediency, each for his own selfish motive -- Monro for the money, Ross to prove a woman can do a dirty job just as well as a man -- Crichton has the essential ingredients of a worthy successor to "the Maltese Falcon" and "the Treasure of the Sierra Madre, similarly sturdily written, rousing tales of greed and daring.

The comparison to other novels which later made classic films is inevitable, because "congo" is obviously tailored for the movies. Crichton, author of "The Andromeda Strain" and "The Terminal Man," has lately been concentrating on directing feature films such as "Westworld," "Coma" and the recent "The Great Train Robbery," based on his novel. It comes as no surprise, then, that character development and reflection are practically nonexistent here. The emphasis is on visuals (computers, video screens, James Bond-like gadgetry) and the story is told through the constant action and hardboiled dialogue. (Casting this one is easy: Lesley-Anne Down or Jane Seymour as Ross, swathed in white, basking in amorality; Robert Duvall as Monro, in "Apocalypse Now" jungle fatigues; Christopher Reeve as Elliot, in designer khakis.)

Having set up his premise, the action comes fast and at regular intervals, with each new vicissitude -- kidnaping, machine-gun fire, unfriendly Pygmies, killer monkeys, cannibals, volcanoes, missile attacks and tsetse flies -- bumping into the next with such impatient impertinence that one suspects Crichton can't wait for the next disaster. What he is patient about, however, is setting an atmosphere of credibility, with elaborate technological, historic and geographic explanations so the onslaught of the fantastic is steeped in some form of realism. Consequently, the novel often reads like a screenplay with footnotes -- a Harlequin romance for male academics.

Nevertheless, it's a fascinating scenario which should have across-the board appeal, except among those who enjoy a touch of eroticism in their jungle best sellers. If you exclude the simian love match at fadeout, no one even thinks about romance on this exotic trek. The men don't make a pass at Ross, the "very flower of virile Texas womanhood," nor does it occur to the supposedly independent heroine to corral a bit of local talent for a tropical tete-a-tete. iThe group, like the narrative, is much too busy in its search for the lost