The Underworld, also known as Duat or Tuat by the ancient Egyptians, is a realm of eternal punishment and suffering, akin to Hell in the Judao-Christian theology. It is a location in The Mummy Returns of The Mummy film franchise.
The souls of those that were doomed in the afterlife as well as those that had committed severe blasphemies, were condemned to the Underworld, such as the High Priest of Osiris, Imhotep, who had attempted to bring his deceased love, the concubine Anck-Su-Namun, back to life by performing a proscribed ritual using the Book of the Dead.
The Underworld was accessible in the Oasis of Ahm Shere, where the Golden Pyramid located in the centre of the Sacred Desert had its stone floors cracked, revealing the Underworld as a deep, fiery chasm filled with dark savage figures reaching out at those that walked close to the cracks.
The Scorpion King, within his pyramid had been defeated at the hands of Rick O'Connell using the Spear of Osiris and sent back to the Underworld; his defeat prompting the pyramid and its surrounding oasis to be taken back into the Underworld as Anubis took back his gift to the Scorpion King. In the midst of the pyramid's removal, O'Connell and Imhotep fell into the crack where the dark, savage figures were, and both men held on as the dark figures pulled them into the abyss. O'Connell's wife Evelyn saw as her husband fell into the pit and was told by O'Connell to leave and take their son to safety, but Evelyn went back to help O'Connell out, while Imhotep called out to Anck-Su-Namun for help, but Anck-Su-Namun did not listen, running away instead and leaving Imhotep to hang onto the ledge himself. Imhotep, being distraught at his abandonment, gave up his life and released his hold on the ledge, allowing the dark figures to take him into the abyss.