The play opens in a lonely cottage on the Aran Islands, where young Cathleen and Nora quietly hide a bundle of clothes sent by a priest from Donegal, suspecting they belonged to their drowned brother Michael. Their mother, Maurya, remains consumed by anxiety as her surviving son, Bartley, insists on sailing to the Galway horse fair despite rising gales and ominous portents. Ignoring his mother's pleas and lacking her blessing, Bartley departs, leaving the household with a lingering sense of foreboding.
As the sisters examine the bundle, matching a dropped stitch on a plain knitted stocking to confirm the clothing belongs to Michael, Maurya returns in deep distress. She recounts a terrifying vision near the spring well, where she saw Michael's ghost riding a grey pony directly behind Bartley, sealing her conviction that her last son is doomed. Her fears are swiftly realized when village women arrive bearing the dripping body of Bartley, who was knocked into the surf by the grey pony.
With all six of her sons and her husband now claimed by the ocean, Maurya reaches a state of profound, resigned peace rather than frantic despair. She lays Michael's recovered clothing across Bartley's remains and sprinkles holy water over them, accepting the inevitable destiny dictated by the sea. The drama concludes with the grieving mother offering prayers for the souls of her entire family, finding solace in the realization that the ocean can take no more from her.
