The central narrative
The Osiris myth
No single text gives the complete Osiris myth. It must be assembled from the Pyramid Texts (c. 2400 BCE), the Coffin Texts, the Book of the Dead, temple reliefs at Abydos, and the later account by the Greek writer Plutarch in De Iside et Osiride (c. 100 CE). The following is the scholarly consensus narrative drawn from those sources.
Osiris rules, and is murdered
In the beginning of divine kingship, Osiris ruled Egypt as a wise and just king, teaching agriculture and law. His brother Set — embodiment of desert, chaos and foreignness — grew envious. Set constructed a richly decorated chest exactly fitted to Osiris's body, then at a banquet offered it as a gift to whoever it fitted. When Osiris lay inside, Set's confederates slammed the lid shut, sealed it with molten lead, and threw it into the Nile. The chest drifted to Byblos (in modern Lebanon), where a great tamarisk tree grew around it and it was incorporated into a palace pillar.
Isis searches and reassembles
Isis, Osiris's wife and sister, set out in search of the body. She recovered the chest from Byblos, brought it back to Egypt, and hid it in the marshes of the Delta. Set, hunting by moonlight, discovered the chest and this time dismembered the body into fourteen pieces, scattering them across Egypt. Isis and her sister Nephthys searched the length of the Nile. They found all pieces except the phallus, which had been swallowed by a Nile perch (or, in some versions, an oxyrhynchus fish). Isis fashioned a substitute, reassembled the body, and with her wings fanned the breath of life back into it long enough to conceive a son — Horus.
Resurrection and the first mummification
Anubis, the jackal-headed god of embalming, performed the first mummification of Osiris's reassembled body, wrapping it in linen and performing the Opening of the Mouth ritual to restore the senses. This act established the template for all subsequent Egyptian funerary practice. Osiris could not return to rule the living world — death, once real, was permanent — but he became king of the Duat, the realm of the dead. Every deceased Egyptian thereafter was ritually identified with Osiris, taking the title "Osiris [Name]" in funerary texts.
Horus versus Set
Isis concealed the infant Horus in the Delta marshes, protecting him from Set. When Horus reached adulthood he challenged Set for the throne of Egypt. Their conflict, spanning eighty years in some accounts, is called the Contendings of Horus and Set, preserved in the Chester Beatty Papyrus I (c. 1160 BCE). The struggle involved battles, legal proceedings before a divine tribunal, and feats of strength. Horus lost his left eye; Set lost his testicles. The eye of Horus — the Wadjet eye — became a powerful protective amulet, symbolising healing and wholeness. Eventually Osiris himself, sending a message from the underworld, persuaded the gods to rule in Horus's favour. Horus was crowned king of the living; Set was not destroyed but assigned rule over the storms and the desert, his chaotic energy redirected to protect Ra's solar barque from the chaos-serpent Apophis each night.