Machinist's Mate 1st class Jake Holman (Steve McQueen) arrives on board the fictional USS San Pablo, a gunboat smaller than but similar to the real-life USS Panay. San Pablo is tasked to protect Americans and patrol the Yangtze River in 1920s China. Holman is placed in charge of the gunboat’s engine room and soon runs afoul of the “coolie” labor system used aboard where local Chinese do all the routine chores thus relieving American sailors who (barely) supervise. Holman becomes alarmed when he sees that his engine room is operated by Chinese coolies who perform their tasks by rote, without understanding the machine they operate. He begins to train Po-Han (Mako Iwamatsu) to a better standard, treating him more as a friend and protégé, which earns him the ire of the rest of the crew. Holman’s few friends include Frenchy (Richard Attenborough) a Senior Petty Officer and missionary school teacher Shirley Eckert (Candice Bergen). Both of them will be in need of rescuing later in the film as the many dangers of 1920s China unfold.