Shortly before Pearl Harbor, American opportunist Jones and partner Johnny are in China to sell oil to the invading Japanese army. Cynical about the sufferings of the Chinese, Jones meets compassionate teacher Carolyn Grant while travelling cross-country to Shanghai. Sparks fly between these strong-willed characters, neither budging an inch. But when Jones witnesses a Japanese atrocity, his feelings toward his customers (and Carolyn) begin to change...

In 1941, in Mei-Ki, China, war profiteer David Jones narrowly escapes with his life when Chinese Captain Tao-Yuan-Kai arrests him for selling oil to the Japanese but releases him because he is American. Japanese planes bomb the town, and Jones drives toward Shanghai with his partner, Johnny Sparrow, who has brought with him an orphaned baby boy. After nightfall, they are forced to stop because Chinese refugees crowd the road and beat the Americans until Carolyn Grant, an American schoolteacher born in China, tells them to stop. Carolyn sneaks her group of female college students into the back of Jones's truck and insists that Jones proceed without headlights because they might be sighted by Japanese bombers. As she has an intimate knowledge of the local terrain, Carolyn takes over driving the truck, and has her friend, Lin Wei, sit on the hood to watch for potholes. When Jones realizes that Carolyn has loaded his truck with refugees, he ruthlessly starts to throw them out, fearing that the extra load will use up the gas he needs to get to Shanghai, but relents when he learns that the students are young women. Along the road the next day, they encounter Lin Wei's first and second brothers, Lin Cho and Lin Yun, who have formed a guerrilla band and are posing as peasants. Lin Cho warns them to take an alternate road, as the Japanese are approaching, and Jones reluctantly heads the truck to the family farm of Tan Ying, a girl he tried to throw off the truck. At the farm, Carolyn tries again to persuade Jones to take the students to Chungtu, where they can continue their studies, rather than Japanese-occupied Shanghai, but Jones is unconcerned with the struggle of the Chinese, and refuses. After Johnny leaves the baby, whom he has dubbed "Donald Duck," with Tan Ying's family for safekeeping, the journey resumes. They are forced to abandon the truck when Japanese planes strafe the road, but Lin Cho and his compatriots shoot the plane down. When Carolyn discovers that Tan Ying has slipped off the bus to rejoin her family, she insists on returning for her. While the rest of the group hikes to a monastery, Jones and Carolyn drive back to the farm and are shocked to find that the Japanese have burned the farm, and murdered Tan Ying's parents and Donald Duck. Jones then finds three Japanese soldiers raping Tan Ying, and shoots them without hesitation, while Carolyn comforts the hysterical woman. After the group takes refuge in the monastery, Tan Ying dies. Finally cognizant of the nature of the Chinese struggle, Jones is now inspired to join the fight against the Japanese, and offers his help to the three brothers. They determine that they must close a mountain pass in order to prevent the further onslaught of the Japanese, but only the Japanese army has the necessary dynamite. That night, Jones, Johnny, Lin Wei, Lin Cho and Lin Yun swim across a river to raid a Japanese encampment and steal the dynamite. When their presence is detected, a fierce gun battle ensues, during which Lin Wei, and all but two other guerrillas, are killed. Before he dies, Lin Wei honors Jones by calling him his "fourth brother." That night, Carolyn rejects Johnny's marriage proposal because she is in love with Jones, and later, the new lovers Jones and Carolyn spend a final night together. The next day, the small band of fighters places the dynamite along the mountain pass road. When the Japanese convoy appears early, Jones stops them on the road to give the guerrillas time to lay the dynamite, and pretends that he is stranded. The Japanese general explains to Jones that Japan has just bombed Pearl Harbor in the United States, and that their intention is to create a new world order. After the general's second-in-command shoots Jones, the Chinese set off the dynamite causing an avalanche that buries the Japanese troops, and closes the road. Carolyn and Johnny mourn the loss of their friend as they drive the students to Chungtu.