Ancient Egypt in the year 1290 B.C.
Ardeth Bay: [narrating] Thebes, City of the Living. Crown jewel of Pharaoh Seti the First. Home of Imhotep, Pharaoh's high priest, keeper of the dead.
Ardeth Bay: [narrating] Birthplace of Anck Su Namun, Pharaoh's mistress. No other man was allowed to touch her. But for their love, they were willing to risk life itself.
The two love one another more than life itself, but as long as Seti lives, they may never be together, leaving them with the plan of assassinating the pharaoh.
As a precaution to ensure that Anck-Su-Namun stayed within Seti's rule, she is painted in several coats of golden body paint, which ensures that no other man might touch her, though the precaution is thrown out when Anck-Su-Namun comes close to Imhotep as the two are in Anck-Su-Namun's residence and the they share a kiss, which ends in Imhotep smearing the paint on Anck-Su-Namun's left arm.
At that moment, Seti, who has just come to Anck-Su-Namun's residence, is surprised to see Imhotep's priests at the residence, but is utterly infuriated when he sees Anck-Su-Namun with the paint on her arm smeared and Seti asks which man dared to touch her.
Imhotep comes from behind the pharaoh and is about to assassinate Seti with a dagger, but ceases as Anck-Su-Namun stabs Seti with another dagger, her lover joining in until Seti is killed. The Medjai, the pharaoh's elite guard, storm the residence, seeking whoever had committed the crime.
The Medjai were too late to catch one of the real culprits as Imhotep leaves the scene at the request of Anck-Su-Namun, who states that only he could bring her back to life were something to happen. Upon discovering Seti's corpse and Anck-Su-Namun with a dagger, the guards watch as Anck-Su-Namun, feigning treachery, stabs herself in the stomach with the dagger used to murder Seti.
Soon after, Imhotep and his priests unearth her body and race into the deserts to seek Hamunaptra, the City of the Dead, where the wealth of kings and the resting place for pharaohs lays.
Here Imhotep seeks the black Book of the Dead so as to revive his love, and began to perform the spell that would bring her to life. But before the ritual can be completed, the Medjai, who had followed the priests as they headed to Hamanaptra, storm the chamber where the ritual is being performed.
To commit an act such as bringing one back from the dead is blasphemy of the worst caliber, and so the priests are all condemned to death by mummification while they were alive. Imhotep, having led them into their sin, is condemned to endure the Hom-Dai, a curse so powerful that it had never before been performed.
The priest's tongue is ritualistically cut out, and he is bound tight in wrappings, placed in a sarcophagus which is filled with flesh-eating scarabs.
As the scarabs eat Imhotep alive, the lid is placed over the sarcophagus, sealed with a key resembling a puzzle-box.
The Medjai and their descendants vow from that time on to watch over the city's ruins so that none might find either Imhotep or the means to bring him back to life.
In 1923 A.D, centuries after the pharaohs of Egypt had fallen, the Medjai still exist, becoming a furtive secret society over the years with the same goal as they did centuries ago: to ensure that none find the ruins of Hamanaptra.
One group of Medjai led by Ardeth Bay stand vigil over Hamunaptra, witnessing a garrison of the US troops, British troops and French Foreign Legion that have found the ruins, setting up their post within the crumbling walls. The Legionnaires in the garrison believed so much that Hamunaptra existed that they trekked across Libya into Egypt, and encountering a great army of Tuareg warriors at the site.
Rick O'Connell, an American serving as corporal in the Legion, has been promoted once the leader of the garrison, Colonel Guizot, deserts the ruins on horseback, leaving his men on their own.
Beni Gabor: You just got promoted.
Rick: [shouting to troops] Prenez vos positions! Steady!
Rick: [to Beni] You're with me on this one, right?
Beni: Oh, your strength gives me strength.
O'Connell leads his fellow Legionnaires into successfully bringing down many Tuaregs, but as the battle wages on, the Tuaregs kill off more and more Legionnaires including 10 US troops and 12 British troops until only O'Connell himself and Beni survive. Beni runs away. O'Connell blasts away many Tuaregs with his pistols, but finds himself outnumbered once his bullets run out.
The Tuaregs chase him into a corner, but can't fire, as their horses are frightened off by something within the sand; with this, the Tuaregs leave Hamunaptra, leaving O'Connell alone to face whatever is in the sand, until the movements in the sand drive him off as well. Running off into the desert, O'Connell notices a group of men on horseback watching him in the distance, Medjai, who decide not to kill him, as the desert would do that.