This medieval Latin work narrates the origins of Saint Finbar, detailing his lineage from the descendants of Bruin and the circumstances of his birth. His father, Amargenus, a blacksmith, faced the wrath of Duke Tyagernacus after marrying a beautiful woman against the duke's wishes. However, divine intervention spared them from execution when the unborn Finbar spoke from the womb, leading to their release. The narrative highlights Finbar's early signs of holiness and the decision by three anchorites to take him under their guidance, indicating his destined role as a saint.