Coronis was born to Phlegyas, the king of the Lapiths in Thessaly, a people famous for their warlike nature and their disastrous encounters with the gods. Her father's brother was Ixion, the Lapith who had murdered his father-in-law, tried to rape Hera, and been bound to a burning wheel in Tartarus for eternity. The house of Phlegyas was not one that produced cautious or pious children. Coronis grew up in the town of Lacereia, near Lake Boebeis in the region of Pelasgiotis, a princess of a kingdom that valued strength over discretion. She was beautiful, and her beauty caught the eye of Apollo, the Olympian god whose oracle at Delphi spoke truth to all who asked, whose lyre charmed the Muses themselves, and whose arrows struck with unerring accuracy.

Apollo came to Thessaly and lay with Coronis. She conceived a child, a son who would one day be called Asclepius, though at the time he was only a promise in her womb. Apollo, being a god, could not remain in Thessaly. He had duties on Olympus, sacrifices to receive at Delphi, and the sun to drive across the sky in his blazing chariot. He left, but he did not leave Coronis unguarded. In the version told by Ovid in his Metamorphoses, Apollo placed a white crow, a bird sacred to him, to watch over the pregnant princess and report any danger. In the older version told by Pindar, no guardian was needed, for Apollo's own prophetic powers made deception impossible. The god of truth, Pindar wrote, cannot himself be deceived. Either way, Coronis was left alone with a secret that would destroy her.

While Apollo was away, a man named Ischys came to Thessaly. He was the son of Elatus, a king of Arcadia, a mortal man of no particular divine distinction but of sufficient charm to turn a princess's head. Coronis, pregnant with Apollo's child, took Ischys as her lover. Some say she married him. Others say the affair was brief and secret. The ancient sources do not explore her motives; in the logic of Greek myth, the act itself was the crime, and the reasons behind it did not matter. What mattered was that a mortal woman who had been loved by a god had chosen a mortal man instead, and that choice was a transgression against the divine order.

The discovery of the betrayal followed two paths in the ancient tradition. In Pindar's Pythian Ode 3, the earliest and most authoritative poetic account, Apollo learned of the infidelity through his own omniscience. No messenger was needed. The god who sees all things at Delphi simply knew, as a prophet knows, and his knowledge was immediate and absolute. In Ovid's Metamorphoses and in the prose handbook of Apollodorus, a white crow witnessed the affair and flew to Apollo to report it. The crow expected reward for its loyalty. It received a curse instead. Apollo, enraged by the news, turned the bird's snow-white plumage to black with a blast of his solar fire, and from that day every crow and raven in the world has worn black feathers. The crow's punishment became a cautionary tale about the dangers of telling truth to power, a story that Chaucer would later adapt in his Manciple's Tale.

Apollo's vengeance was swift and absolute. In Pindar's version, he sent his twin sister Artemis, the virgin huntress goddess who enforced boundaries and punished transgressions of purity, to Lacereia with her bow. Artemis struck Coronis down with her arrows, and the destruction did not stop with the princess alone. Pindar describes the death spreading outward like fire from a single spark that consumes an entire forest on a mountainside. Many of Coronis' neighbours perished alongside her, innocent bystanders caught in the divine wrath. In other versions, including those of Ovid and Hyginus, Apollo killed Coronis himself, striking her with his own arrow or thunderbolt. Ischys also died, slain by a thunderbolt of Zeus in some accounts, or by Apollo's own hand in others. The house of Phlegyas was destroyed, razed by the god whose love the princess had thrown away.

The most extraordinary moment of the myth came after the killing. Coronis' body was placed on a funeral pyre, and the flames were lit. As the fire consumed her, Apollo was seized by remorse, or by concern for his unborn child, or by both. He approached the burning pyre and, in an act that fused grief with divine purpose, snatched the living infant from his dead mother's womb. The child was Asclepius, and the rescue constitutes the first recorded caesarean delivery in Western literature. Pindar says Apollo himself performed the extraction. Apollodorus says it was Hermes, the messenger god who guides souls between life and death, who cut the child from the flames on Apollo's behalf. Either way, the infant was alive, pulled from death by divine power. Apollo then entrusted the child to Chiron, the wise centaur who lived on Mount Pelion, and Chiron raised Asclepius in the arts of medicine and hunting. The boy who had been born from fire would grow up to become the greatest healer in Greek myth, a physician so skilled that he could cure any disease and eventually learned to raise the dead, a power that would bring Zeus himself to strike him down with a thunderbolt.

Coronis' story did not end with her ashes. Some ancient sources, including the historian Istrus, said that she was placed among the stars as the constellation Corvus, the Crow. The connection was obvious: her name, Korônis, meant "crow" in Greek, and the bird that had brought about her downfall was the same bird that would bear her name in the sky. The constellation Corvus is a small quadrilateral of stars near the constellation of the Virgin, visible in the southern sky on spring evenings. It is not a bright constellation, but it has endured, a faint memorial to a princess who chose a mortal lover over a god and paid for that choice with her life and her body.