Deirdre was the daughter of Fedlimid, the storyteller to King Conor MacNeasa. Before she was born, she gave a terrible shriek from her mother's womb that terrified all that heard it. Cathbad the Druid foretold that the unborn child would turn out to be the most beautiful woman in Ireland, that men would fight over her causing terrible destruction, and that she should be killed at birth to forestall disaster.

But King Conor MacNeasa refused to give the order for the infant's death. Instead he decreed that she should be brought up in seclusion, having nothing to do with any man, until she came of an age when he himself would marry her. She was given into the care of Leabharcham, a wise and satiric woman, to be raised as a fitting bride for a King.

Deirdre grew up in the charge of her nurse, never seeing a man, and becoming accomplished in skills befitting a noble woman. One day she saw from her window the slaughter of a calf, and declared she would only love a man who had the three colors she saw there before her: skin as white as the snow on the ground, cheeks as red as the blood which flowed from the slain calf, and hair as black as the raven that had swooped down to feed on the carcass.

Leabharcham declared that such a man already existed! His name was Naoise, and he was the son of Ushna. Deirdre went into a decline from that moment, ailing until such time as she should meet this man, so Leabharcham arranged for him to go hunting near to where she and Deirdre lived. Deirdre ran out to meet him, and begged him to elope with her. He tried to refuse since he knew the orders of King Conor MacNeasa. But Deirdre refused to release him, leaving Naoise with no choice but to summon his two brothers before they all left Ulster together.

Naoise and Deirdre were happily married, and loved each other dearly. But King Conor MacNeasa would never allow them any peace, and sent many men after them to retrieve Deirdre. Naoise and his brothers were almost invincible when they fought together, killing many of Ulster's best men, and so King Conor had to resort to trickery.

He sent a message via Fergus MacRoigh, his chief advisor, who stood guarantor for the King's good behavior. Deirdre and the sons of Ushna were told that they could return in safety to Ulster, that the King no longer bore them malice. But Deirdre warned the brothers that the King's intentions were not honorable. Not heeding her advice, Naoise and his brothers returned to Ulster where they were set upon by mercenary allies of the King who finally overpowered and killed them all.

After that it is said that Deirdre was taken into captivity by King Conor, and made to live with him for a year, during which time she never laughed nor slept. One year after the death of Naoise, King Conor brought her to meet Eogan MacDurthacht, the killer of her husband. She was thus caught between the two men she hated most on earth, and in a rage and despair she dashed her brains out on a standing stone that was before her, rather than suffer any further torment.

Another legend has it that Deirdre was so overwhelmed with grief at the sight of Naoise's dead body that she cast herself on to it, mourning loudly, dying instantly of a broken heart.

Deirdre! The most magnificent beauty of Ireland, denied her true love by a jealous King, finding peace only in death.