CHINA DAWN By Robert L. Duncan Delacorte. 590 pp. $18.95

Not since James Clavell's "Shogun" enlightened readers on the early history of Japan has a novel done a better job in dramatizing the Orient than Robert L. Duncan's sweeping epic "China Dawn."

Yuki Nakamura is 15 in 1931 when her peasant father sells her into prostitution for the price of the ox that will keep his family from starvation. American missionaries help her escape from the Yoshiwara, Tokyo's red-light district, and smuggle her off to Shanghai, where they have arranged a job for her in the American consulate. There she meets the two men who will shape her future -- Vice Consul Sam Cummings and Sam's diplomatic colleague, the Japanese aristocrat Colonel Ito.

So begins an intricate web of relationships that over the years will test the trio's ties of love, fidelity and duty.

The day he arrives in Shanghai, Sam's superior, Consul Alcott, gives him a succinct analysis of China's political and military situation. China, he says, is "a collection of generals and warlords trying to kill each other while the Nationalists and the Communists try to recruit them all. And China will be lost in a battle between the Nationalists and Communists if Japan doesn't destroy her first."

Washington's position, the consul says, is that "we Americans are to remain neutral, which means, of course, that American business is free to sell goods to either belligerent party."

Although Shanghai has been declared an open city, Chinese and Japanese war on each other there while the Western nationals in the International Settlement look on with amused detachment. The Chinese sector is dominated by General Wang, a warlord who extorts money from every enterprise and rules by terror. At his first meeting with Wang, Sam is horrified to see the general's soldiers casually beheading a civilian. Wang's bloody tactics reappear at a later stage when he forces Colonel Ito to watch while he mutilates and then executes 11 Japanese businessmen whom his troops captured, along with Ito, in a raid on a railroad train. He then humiliates the proud Japanese officer by covering him with excrement before releasing him.

Scenes of barbaric cruelty abound. Sam, en route to Nanking, sees drunken Japanese soldiers urging dogs to attack two Chinese men who have been buried to the waist; he witnesses Chinese civilians set on fire, and looks on helplessly as 10 schoolgirls are raped and slaughtered.

But not all is horror. Threading the narrative are strands of tender romance and noble sacrifice. Yuki and Sam are so much in love that Sam is ready to ruin his career by divorcing his wife, but a pregnant Yuki, unwilling to have Sam pay such a price, runs away and is sheltered by Ito, who becomes her protector, her lover and surrogate father to Yuki's daughter, Dawn.

Sam and Ito, decent and honorable men, are bound in friendship by their mutual desire to avoid war, but both suffer for their integrity. Sam, furious over America's stubborn passivity in the face of Japanese atrocities, makes his feelings known to the State Department and is punished by demotion to a lesser post in Singapore. Ito incurs the displeasure of Japan's prime minister by questioning the wisdom of his country's militaristic aims. He is exiled to Japanese-occupied Manchuria.

While both men survive the war that follows Pearl Harbor, each pays a price. Sam spends four years in a Japanese POW camp before Ito locates him and arranges his release. Ito is tried as a war criminal. Sam testifies in his behalf, but when the prosecutor threatens to reveal the two men's involvement with Yuki, Ito pleads guilty to all charges.

Over the years, Yuki demonstrates a shrewd head for business and builds a profitable career in women's fashions, helped by Dawn's talent for design. Finally, in 1981, mother and daughter are in Paris readying the first showing of the House of Dawn in 1981 and must confront sabotage by unknown enemies whose motives stem from the turbulent past.

Some colorful subsidiary characters populate this action-packed saga. There is Harry Connaught, an amoral wheeler-dealer who knows every secret and every shortcut in Shanghai. There is Sam's mother Adele, who tries to save her son's reputation through bribery.

This is not a flawless novel. Some motivations are shallow, some incidents are contrived, there are a few needless digressions, but these are readily overlooked in the swift pace of the narrative and its ever-changing landscape. There is really no evading the cliche' -- "China Dawn" ranks with the best of the page-turners.

The reviewer is a writer and editor living in New York.