In South Africa during the 1910s, the story unfolds around the daring adventurer, Allan Quatermain (Richard Chamberlain), a skilled white big-game hunter and intrepid explorer. His expertise becomes essential as he is recruited by the determined Jesse Huston (Sharon Stone), a young American woman ardently seeking to locate her father, who mysteriously vanished during an expedition in search of the legendary King Solomon's Mines. Together, they embark on a thrilling quest into the heart of uncharted territory, aided by Umbopo (Ken Gampu), his enigmatic African companion, as they pursue clues purportedly authentic on a map that promises to lead them to their destination.
However, the stakes rise dramatically when it becomes evident that Jesse's father, Professor Huston, is ensnared by a competing German military expedition led by the ruthless Colonel Bockner (Herbert Lom), a man characterized by his singular focus and a penchant for culinary delights like knackwurst. This cruel expedition is further complicated by the presence of Dogati (John Rhys-Davies), a brutal Turkish slave trader and adventurer, who leverages his intimidating resolve to outmatch Quatermain and his team. Professor Huston, under duress, finds himself interpreting a second map believed to be equally genuine.
As the two factions inch closer to their mutual goal, an intense rivalry ensues, leading to several harrowing encounters that test their resolve. Their journey thrusts them into the dominion of the Kukuana tribe, where both groups fall into the clutches of the tribe's formidable evil priestess, Gagoola. In one particularly harrowing moment, Quatermain is hung upside down over a crocodile-infested pond, leaving everyone questioning his fate. Just as despair threatens to consume them, Umbopo reveals his true identity as an exiled tribal chief, thus reclaiming his rightful position among the Kukuanas. As he commands the allegiance of the tribe, Gagoola seizes Jesse and retreats into the depths of the Breasts of Sheba—the twin peaks that conceal the mines.
The ensuing chaos sees Bockner and Dogati assault the village fiercely. Despite their efforts, they are thwarted by a treacherous moat of quicksand that hampers their advance. Bockner, showcasing a particularly cold demeanor, orders his men forward, leading to their demise. In an act of betrayal, Dogati murders Bockner’s soldiers and uses their lifeless bodies to create a makeshift pathway across the moat. A fierce confrontation ensues, resulting in Bockner shooting Dogati, attempting to salvage the remnants of his team.
Once inside the legendary mines, Quatermain and Umbopo heroically rescue Jesse and stumble upon an astonishing sight—a repository of the ancient tribal queens, featuring the Queen of Sheba encased in splendid crystal. It becomes clear that Gagoola had intended to sacrifice Jesse, leveraging her striking resemblance to maintain her iron grip over the Kukuanas. Just then, Gagoola appears, mocking Umbopo, leading to an electric chase through the tunnels.
As Bockner and his men pursue them, Quatermain and Jesse inadvertently discover a treasure trove filled with sparkling diamonds. Their elation quickly turns to panic when Gagoola activates a hidden switch that traps them within a submerged chamber, setting off a terrifying chain of events with the room slowly filling with water. Just as they brace for the worst, a sudden explosion caused by dynamite set outside sends them cascading from the chamber in a powerful deluge of water.
Bockner, now greedy for treasure, is astonished when a seemingly dead Dogati reappears, equipped with protective gear that saved him from Bockner’s earlier assault. In an act of twisted revenge, he forces Bockner to swallow diamonds, with a sinister plan to extract them later. Meanwhile, as Gagoola evades justice, she chooses a fiery death by plunging into a volcano's shaft, igniting a catastrophic explosion throughout the mines.
As the underground world collapses around them, Quatermain, Jesse, and Umbopo race against time to escape the tightening grips of destruction. In a desperate stand, they navigate a treacherous lake filled with deadly traps, only for Bockner to confront them, demanding the diamonds they retrieved. With quick wit, Quatermain tricks him into falling into the lake, where he is met with the jaws of a mythical water creature.
As they forge ahead, the environment deteriorates, riddled with fire and debris. Quatermain signals for Umbopo to lead Jesse to safety while he confronts Dogati, who has surprisingly emerged from the ruins. A grueling battle ensues, and in a final moment of triumph, Quatermain prevails, sending Dogati into the molten depths below. Just in the nick of time, Quatermain narrowly escapes the erupting volcano, sealing the fate of the mines.
Returning to the tribe, Umbopo takes his rightful position as the leader of the Kukuanas, bidding an emotional farewell to Quatermain and Jesse. As they exit the village, it’s revealed that both have kept a diamond as a poignant reminder of their harrowing adventure. The film culminates in a touching kiss shared by the duo outside the village gates, a testament to the bonds forged through their perilous journey.
