In 3067 B.C., a formidable warrior known as the Scorpion King commands an army intent on world domination. However, they ultimately meet defeat and are banished to the arid enclave of Ahm Shere. In his dying moments, the King pledges his soul to Anubis in exchange for the might to vanquish his foes. Anubis agrees, conjuring a lush oasis complete with a golden pyramid and gifting the Scorpion King an army of jackal-like warriors to conquer Egypt. Yet, after his conquest is achieved, Anubis claims the King's soul, returning the army to the depths of the Underworld.
Fast forward to 1933 A.D., seven years after the fall of Imhotep, where Rick O’Connell and his wife, Evelyn explore ancient ruins alongside their son, Alex. During their adventure, they stumble upon the mythical Bracelet of Anubis.
When the bracelet mysteriously binds itself to Alex, he begins experiencing visions that compel him toward Ahm Shere. Meanwhile, Evelyn finds herself under attack, captured by a fanatical cult intent on resurrecting Imhotep using the Book of the Dead. Their goal is to harness his power to overthrow the Scorpion King, thereby gaining control over Anubis’ undead army.
The cult, led by museum curator Baltus Hafez, includes the merciless enforcer Lock-Nah and Meela Nais, who is the physical reincarnation of Imhotep’s lost love, Anck-su-namun. Determined to rescue Evelyn, Rick teams up with Alex and Jonathan, Evelyn's brother, who possesses a mysterious golden scepter, alongside the combat-ready Ardeth Bay, a Medjai who returns to aid them.
Amidst grand battles, Rick rescues Evelyn, but their joy is short-lived as Alex is soon abducted and forced to guide the cult through his bracelet-induced visions. The O'Connells chase after them with the help of Rick's associate, Izzy. Along their perilous journey, Alex cleverly leaves clues for his parents, who navigate the skies in Izzy's dirigible.
Meanwhile, Imhotep exploits the Book of the Dead to restore Anck-su-namun’s soul into Meela's body, inadvertently triggering a flood of memories within Evelyn as Princess Nefertiri, the bracelet’s rightful protector and the daughter of Pharaoh Seti I.
As they reach the edge of the oasis, Imhotep, sensing their pursuit, uses his sorcery to bring down the dirigible, with Izzy choosing to stay behind for repairs. The O’Connells infiltrate the cult, but both factions find themselves surrounded by terrifying pygmy mummies. In the ensuing chaos, Rick rescues Alex while Ardeth confronts and slays Lock-Nah.
The pygmies eliminate most of the cult members, leaving only Hafez, Imhotep, and Anck-su-namun. The O'Connells arrive at the pyramid just as the bracelet separates from Alex. Anck-su-namun, Imhotep, and Hafez then murder Evelyn before entering the pyramid.
Inside, Imhotep discovers that his powers have been stripped, forcing him to battle the Scorpion King as a mere mortal. Hafez uses the bracelet to summon Anubis' army, which emerges menacingly around the oasis. In the thick of battle, Rick challenges Imhotep, but the colossal Scorpion King interrupts their duel. Harnessing cleverness, Imhotep tricks the beast into turning on Rick while Ardeth and his Medjai companions engage Anubis’ resurrected forces.
In a significant twist, Jonathan and Alex manage to liberate the Book of the Dead from Anck-su-namun and use its power to bring Evelyn back to life. Rick uncovers ancient hieroglyphs revealing that Jonathan’s scepter is the Spear of Osiris, a mystical artifact crucial for their final stand. United, Rick, Jonathan, and the revived Evelyn confront the Scorpion King, slaying him and sending both the King and the army back to their underworld prison.
As the oasis begins to collapse and the pyramid crumbles, Rick hangs precariously on a ledge, urging Evelyn to flee while there’s still time. She risks everything to pull him to safety. Observing this, Imhotep, despondent, calls for Anck-su-namun to save him, but she chooses to abandon him. Heartbroken, he lets go and plummets into the abyss. Anck-su-namun’s fate is sealed as she inadvertently falls into a pit filled with scorpions.
At the brink of disaster, Izzy arrives piloting a modified dirigible, rescuing the O'Connells just in the nick of time before the oasis and pyramid are obliterated. As they journey into the sunset, Jonathan mischievously pockets the pyramid's diamond capstone, while Ardeth Bay offers a respectful salute before riding away into the horizon.
