As the play begins, Maurya is a poor Irish woman who has lost her husband, her father-in-law, and her first four sons to the sea. Her fifth son Michael, also feared drowned, has been missing far too long to hold out hope for his return. Her youngest and only remaining son, Bartley, plans to take two horses (a mare and a pony) to market, which will require that he must also go into the sea. Bartley must ride the mare and lead the pony through the waters to reach the ship anchored off shore that will deliver the animals to the market. Maurya begs him to stay, fearing that she will lose her last son. Bartley insists. Their harsh poverty drives him in his actions. As he leaves, his mother cannot give him a blessing, but he blesses her.
In the play's tragic conclusion, while Maurya is being persuaded that Michael is indeed dead, word comes to her that Bartley has been drowned trying to reach the ship with his horses. Maurya has now lost all the men she loved to the sea. Having no more sons to lose, she finds an ironic peace as she blesses Bartley's body with Holy Water and prays for God's mercy.