Allan Quatermain, an adventurer and white hunter based in Durban, in what is now South Africa, is approached by aristocrat Sir Henry Curtis and his friend Captain Good, seeking his help finding Sir Henry's brother, who was last seen travelling north into the unexplored interior on a quest for the fabled King Solomon's Mines. Quatermain has a mysterious map purporting to lead to the mines, but had never taken it seriously.

However, he agrees to lead an expedition in return for a share of the treasure, or a stipend for his son if he is killed along the way. He has little hope they will return alive, but reasons that he has already outlived most people in his profession, so dying in this manner at least ensures that his son will be provided for. They also take along a mysterious native, Umbopa, who seems more regal, handsome and well-spoken than most porters of his class, but who is very anxious to join the party.

At the beginning of the book, Allan Quatermain's only son has died and he longs to get back into the wilderness. He persuades Sir Henry Curtis, Captain John Good, and the Zulu chief Umslopogaas to accompany him, and they set out from the coast of east Africa into the territory of the Maasai. While staying with a Scottish missionary, Mr. Mackenzie, they run into a group of Maasai who kidnap Mr. Mackenzie's daughter.

The Maasai demand the life of one of the party as ransom, but instead they lead an attack on the Maasai, catching them by surprise and slaughtering them. The group then travel by canoe along an underground river to a lake in the kingdom of Zu-Vendis beyond a range of mountains.  At the time of the British party's arrival, they are ruled jointly by two sisters, Nyleptha and Sorais. The priests of the Zu-Vendi religion are hostile to the explorersl, but the queens protect them.