Short summary - Tochmarc Étaíne
Three sagas, known from the Book of Brown Cows and the Yellow Book from Lekan (XIV century), are preserved under this name.
In the old days, Ireland was ruled by a king from the clan of the Goddess Tribes named Eochaid Allotar (Eochaid "Father of All"). He was also called Dagda, for he knew how to work miracles and had power over the harvest. Having wished closeness to the wife of Elkmar, the ruler of Brug, Dagda joined with her when her husband went on a visit. Dagda dispelled the darkness of the night, making the journey so long that nine months passed like one day, and before the return of Elkmar the woman gave birth to a son named Aengus.
Dagda carried the boy to Midir’s house. Engus excelled all the youths in his charming appearance and dexterity in games. He was also called Mac Oak («Young»), for his mother said that truly young was he who was conceived at dawn and born before sunset. Angus thought that Midir had a son and did not suspect his kinship with Dagda. But once they called him a stepson, not knowing his father and mother, and in tears he appeared to Midir. Then Midir brought the young man to Eokhaid, so that his father recognized his son. Eauheid taught him how to take possession of Elkmar, and Mac Oak became ruler of Bruga.
A year later, Midir visited his pupil. Young men played on the field. Suddenly, a dispute erupted between them, and one of them accidentally poked Midir's eye with a rod from a holly, but at the request of Engus healed his healing god Dian Keht.
Then Midir wanted intimacy with the most beautiful girl in Ireland, it was Etain Ehride, the daughter of the ruler of the north-eastern kingdom. Mack Ok came to him and offered a ransom for the bride. The king demanded that the twelve valleys be cleared of the forest - and by the will of Dagda, this was accomplished in one night. Then the king ordered to take the twelve rivers to the sea - and by the will of Dagda, rivers appeared on one night, which no one had heard of before. Then the king said that enough has been done for the good of the earth and he wants to get his share - as much gold and silver as the girl herself weighs. This was done, and Mack Oak led Etain away. Midir was very pleased with his adoptive son.
A year passed, and Midir began to gather home, where his wife was waiting for him. Mac Oak warned the named father that the power and cunning of an insidious woman are great - versed by Fuamnah in the secret knowledge of the Tribes of the Goddess Danu. When Midir brought the royal daughter, Fuamnach met both of them with affectionate words and invited them to her chambers. Etain sat on the bed, and Fuamnach hit her with a red rowan rod, turning it into a large puddle. The heat from the hearth pulled the water, and a worm crawled out from there, which then became a red fly. It was not more beautiful than this fly in the world, and her voice was sweeter than the songs of bagpipes and horns. Any disease was healed by drops falling from its wings, thirst and hunger disappeared from anyone who saw its radiance and sensed aroma. When Midir went around his possessions, a fly accompanied him everywhere and protected him from evil intentions. Then Fuamnach lifted a mighty wind that carried away Etain.
For seven years the fly of rest did not know - completely exhausted, she took refuge on the chest of Mac Oka. Mac Oak dressed her in a purple robe, settled in a glass of sunny peace and began to look after her until she regained her former beauty. Upon learning of Mac Oka’s love for Etain, the Fuamna again sent a whirlwind that brought a fly to the house where people feasted. Etain fell into the golden bowl that stood in front of Etara's wife, and the woman swallowed her with a drink. That was the second time that Etain was conceived.
The daughter of Etara began to call her - after her first conception a thousand and twelve years passed. But Fuamnach fell at the hands of Mac Oc, for he did not forgive the disappearance of the fly.
Eochaid Ayrem ruled Ireland then, and all five kingdoms of the country obeyed him. But Eauheid did not have a wife, so the Irish did not want to go to him at the festival. Ehayid ordered to find the most beautiful girl, which has not yet been touched by a man, and they found him such - Etain, daughter of Etara. Eokhaid’s brother Ailil had a passion for her and, not daring to admit to anyone, fell ill with longing. He was near death when Ehayde decided to go around his possessions.
The king left his wife with his dying brother, so that she would follow the proper execution of the funeral rites. Etain came to Ailil every day, and that made it easier. Soon she realized that the cause of his illness was love. Etain promised to heal Ailil, but, not wanting to disgrace the king in his house, she made an appointment on a hill.
A man came who looked like Ailil in everything, and Etain comforted him. The next morning, Ailil began to lament that he had overslept the meeting, and Etain again invited him to the hill. This was repeated three times: Ailil tried in vain to fight the dream, and Etain comforted the one who had a similar appearance to him. Finally, she demanded an explanation, and the stranger said that his name was Midir - he was her husband when she was called Etain Ehride, but they had to leave because of the Faunnach charms. Etain replied that she would leave with him if Ehayde's consent was obtained. When she returned to the royal chambers, Ailil told her that he was completely healed of both illness and love. And Eauheid rejoiced when he found his brother alive and healthy.
On a clear summer day, Eokhaide Ayrem climbed the walls of Tara. Suddenly an unfamiliar warrior appeared in front of him with golden hair and blue eyes, in a purple cloak, with a five-pointed spear and a precious shield. The warrior said that his name was Midir and he came to test the king in the game of fidhell. He took out a Midir board made of pure silver with golden figures - a gem shone in every corner of it. Midir put up fifty magnificent horses, and Eauheid won them.
The next day, Midir put at stake fifty three-year-old pigs, fifty swords with a golden hilt, and fifty red-eared cows. Ehayid won this mortgage. Then Midir suggested that they play on what each of them wishes. Eauheid agreed, but Midir won that day and said he wanted to kiss Etain. Ehayid gathered the best warriors and brave men in the palace - they surrounded the king from Etain when Midir appeared. He hugged Etain and carried her with him through a hole in the roof, and then everyone saw two swans in the sky above Tara.
By order of the king, the Irish began to crush the magical hills, but the sides who lived there said that they did not abduct Eokheid's wife - in order to get her back, she had to throw away blind puppies and kittens every day. Ehayid did so: Midir was furious, but could not do anything and promised to return Etain. Fifty women were brought to the king, looking like Etain with their faces and clothes. For a long time Echoid chose among them, and finally it seemed to him as if he recognized his wife. The Irish rejoiced, but Midir said it was his daughter from Etain. So Ehayide forever lost his wife, and then was killed by Sigmal, the grandson of Midir.