The plot follows the novel more closely than does any other Tarzan movie. John and Alice Clayton take ship for Africa. Mutineers maroon them. After his parents die the newborn Tarzan is taken by a great Ape, Kala. Later the boy finds his father's knife and uses it to become King of Apes. Binns, the sailor who saved the Claytons and who has been held by Arab slavers for ten years, finds the young Tarzan and then heads for England to notify his kin. A scientist arrives to check out Binns' story. Tarzan, now a man, kills the native who killed Kala; when their chief is killed the black villagers appease Tarzan with gifts and prayers. The scientist's daughter Jane is carried off by a native, rescued by Tarzan (who has burnt the native village), aggressively loved by him ("Tarzan is a man, and men do not force the love of women"), and at last accepts him with open arms.

Charlie is in boot camp in the "awkward squad." Once in France he gets no letters from home. He finally gets a package containing limburger cheese which requires a gas mask and which he throws over into the German trench. He goes "over the top" and captures thirteen Germans ("I surrounded them"), then volunteers to wander through the German lines disguised as a tree trunk. With the help of a French girl he captures the Kaiser and the Crown Prince and is given a statue and victory parade in New York and then ... fellow soldiers wake him from his dream.