The poem commences by Oisin asking St Patrick if he had ever heard the tale of the chase; and on receiving an answer in the negative, accompanied with a request that it may be told truly, he feels indignant at the suspicion that he or any of the Fionna Eironn could ever deviate from the strictest veracity, and retaliates by declaring how much he prized his former friends, whose virtues he records, beyond Patrick and all his psalm-singing fraternity. Patrick, in reply, exhorts him not to indulge a strain of panegyric which borders on blasphemy, and extols the power of that great Being by whom all the Fenian race had been destroyed. The mention of his friends’ extinction calls forth a fresh burst of indignation from Oisin, and leads him to compare the pleasures of the days gone by with the melancholy occupations of psalm-singing and fasting. Patrick requests him to cease, and not incur the impiety of comparing Finn with the Creator of the universe. Oisin replies in a style more indignant, and after reciting a number of the glorious exploits of the Fenians, asks by what achievements of Patrick’s Deity they can be matched. The saint, justly shocked by such daring, accuses him of frenzy, and tells him that Finn and his host have been doomed to hell-fire by that God whom he blasphemes: but this only provokes Oisin to make a comparison between Finn’s generosity and the divine vengeance; and as for himself, it is a sufficient proof of his sanity that he allows Patrick and his friends to wear their heads. Patrick, as if tacitly admitting the validity of his argument, pays him a compliment, and requests him to proceed with the promised tale. Oisin complies, and informs him that while the Fenian heroes were feasting in the tower of Almhuin, Finn having withdrawn from the company and spied a young doe, pursued her with his two hounds Sceolan and Bran as far as Slieve Guillin, where she suddenly disappeared. While he and his hounds are left in perplexity, he hears a sound of lamentation, and looking round espies a damsel of surpassing beauty, whom he accosts, and with friendly solicitude asks the cause of her grief. She replies that she had dropped her ring into the adjoining lake, and adjures him as a true knight to dive into the water to find and restore the lost treasure. He complies, and succeeds; and while handing her the ring, is suddenly metamorphosed into a withered old man.