Like all such stories which live a long life, and this story is at least seventeen centuries old, it concerns a love triangle. A familiar triangle, the old king, his young wife, the trusted knight.
The three involved in our story is the great Fionn mac Cumhaill (Finn Mac Cool in English), the beautiful but headstrong Grainne, and the noble young warrior, Diarmuid Ua Duibhne.
It’s a saga of magic, sorcery, murderous mayhem, bloody vengeance, relentless pursuit and a final act of treachery.
Fionn mac Cumhaill was the leader of the Fianna tribe and was growing old. Despite his age, he decided to get married and he chose to marry Grainne, the daughter of the High King at Tara. Grainne did not want to marry Fionn mac Cumhaill he was an old man and could not find it in her heart to love him.
At the wedding feast, her eye caught sight of a handsome young warrior named Diarmuid. As quickly as she could she put a sleeping potion in the guest’s drinks, except Diarmuid, and as soon as they were all asleep, she begged him to taker her away from her unwanted marriage.
Diarmuid did not want to be disloyal to Fionn but he weakened under the pleading of the beautiful Grainne. The couple ran to the stables and stole a cart and pair of horses and made their escape whilst Fionn and the others were still sleeping.
Finn woke up to discover his new wife missing. Not only had he lost his wife before he had consummated the marriage, but he had also lost his trusted lieutenant and one of his best soldiers. Finn ordered that all the men of the tribe and their dogs should search through the land looking for the missing couple.
The tribe was not far behind the missing pair, and neither stopped for refreshments or sleep. Chancing upon Diarmuid’s foster father they received succor in the form of a magic cloak which made them invisible and let them sleep, eat and drink. The couple used the cloak for sixteen years, sleeping rough and taking food and drink from where they could find it.
Fionn mac Cumhaill was still alive and when approached by Grainne’s and Diarmuid’s families he agreed to stop the hunt as long as the couple agreed to return and Grainne was not flaunted in front of him. A feast was held to make their return and Diarmuid’s lands were returned to him and peace and prosperity returned to the kingdom.
Outwardly Fionn had forgiven Diarmuid, but inwardly he was still seething with anger. Fionn received a prediction that Diarmuid would die if he hunted for the Boar of Boann Ghulban. Telling no one of this prediction Fionn asked Diarmuid to lead an expedition to capture the Boar.
The prediction was fulfilled and Diarmuid lay dying. Fionn was blessed with magic powers. If he cupped his hands, filled then with water and gave it to a dying man, then he could save their life. Fionn made two attempts to carry the water back from the stream but each time he managed to trip and spill the water.
On his third trip, Fionn was given support and not allowed to trip, but by the time he got to Diarmuid, he was dead. The old man had exacted his revenge on the warrior without anyone noticing.