The events described take place in ancient Thebes, Egypt, in 1290 BC. Imhotep, a high priest, engages in a forbidden relationship with Anck-su-namun, the mistress of Pharaoh Seti I. When their affair is discovered by the Pharaoh, the two conspire to murder him. Following the assassination, the Pharaoh's bodyguards, known as the Medjai, arrive at the scene. To avoid capture, Anck-su-namun takes her own life while Imhotep escapes, intending to bring her back to life.

Imhotep, along with his loyal priests, retrieves Anck-su-namun's body and journeys to Hamunaptra, referred to as the City of the Dead, to perform a resurrection ritual. However, their efforts are interrupted by the arrival of the Medjai. As punishment for their actions, Imhotep's priests are mummified alive. Imhotep himself is subjected to a particularly severe curse: he is buried alive with flesh-eating scarabs, ensuring an eternity of torment.

The Medjai, recognizing the catastrophic potential of Imhotep's resurrection, vow to guard against his return. It is believed that should Imhotep rise again, he would unleash an unparalleled and unstoppable evil upon the world.