King Solomon's Mines is unified by many meaningful themes, the broadest of which is the struggle between good and evil embodied in the heroes' quest to discover the fate of Sir Henry Curtis's lost brother. Like many heroes of ancient myths, Quatermain and his comrades must overcome obstacles imposed either by the forces of nature (e.g., the merciless heat of the desert, the treacherous cold of the mountains) or by evil powers, embodied in Twala, the usurper king of the Kukuana people, and his hideous sorceress, Gagool.

Though they are somewhat "larger than life," Quatermain, Sir Henry, and Captain Good are not merely embodiments of abstract moral principles. They are depicted as real human beings who find themselves in extraordinary situations. Nevertheless, as Captain Good's name implies, they do represent the forces of "good" in a battle against evil.

The evil characters are...