A stranger appears at young Ronan’s Irish countryside house in 1951, and, in exchange for dinner and a bed, spins legends of long-ago knights, kings, and tyrants. Ronan is captivated by the storyteller’s accounts of Patrick, pre-sainthood, and the building of Newgrange (an Irish stone structure that predates Stonehenge). When his chilly mother, Catholic sensibilities offended, banishes the old man from the house, Ronan begins a lifelong quest to find the man and solve the mysteries of his family’s past, while forging his own career as a historian. Part period saga, part domestic drama, Ireland sometimes strains with over-wrought prose (”the echo of a sob tripped his breath”). But Delaney gracefully collects essential myths — and invents a few, too — in his heartfelt ode to the oral tradition.