The legend of Finn Mac Cumhail is varied at best. What follows is a generally agreed upon synopsis:
- Finn's father Cumhail, a Fianna chieftain, was mortally wounded and killed in battle by Goal Mac Morn, the leader of a rival clan, before Finn's birth.
- Terrified for her new baby's survival, Finn's mother sent him away intrusting him to two of her closest colleagues - a druidess named Bodbal and a woman warrior named Fiachel.
- Together these women successfully raised Finn in secret hidden deep within the mountains of Erinn (Ireland). During this time they taught him all the lessons and skills he would need to survive he set out to avenge his father's murder.
- When it was time Finn ventured out and served under several kings who immediately sent him away, in fear of a retaliation from Mac Morna, after they discovered who he was.
- Discouraged, Finn wandered throughout Ireland until he met an old poet living near the river Boyne whom he ended up studying under for seven years.
- At one point, near the end of these seven years, he was charged with catching the Salmon of Knowledge and cooking it for his master, being told not to eat it. Whilst it cooked he burst a blister on the Salmon and inherited its wisdom. He know possessed what was needed to challenge Mac Morna.
- Gathering 150 of the bravest and best of the Fianna, Finn sought revenge on Goll Mac Morna. The battle was long, lasting a few days, but in the end Mac Morna's men were no match for the Fianna and Goll Mac Morna died on Finn's sword.
Finn and the Fianna continued to fight in great battles and were acknowledged figures in Celtic history. It was said that in the fields of daring, courageousness, and skill the Fianna were unequaled and that no man could hope to be better in magic, poetry, or wisdom then Finn Mac Cumhail.