Mac Con, exiled from Ireland, returns with the aid of the king of Britain, along with an army of Britons and Saxons, and conquers Ireland as far as Connacht where Éogan, with the help of Art mac Cuinn, plans to fight. The night before the battle Éogan and Art sleep with their hosts' daughters, conceiving the sons who will succeed them, Fiachu Muillethan in Éogan's case and Cormac mac Airt in Art's. Both Éogan and Art, as is foreseen, die in the battle at Mag Mucrama, and Mac Con becomes king of Tara.