Set in the troubled days of the 1798 Rebellion, The Powder Monkey is the story of a boy, Donal Long, who steals a boat to escape his violent uncle and is picked up by a British warship. He is adopted by the ship's crew and becomes the "powder monkey" whose job it is to carry powder to the guns.
Donal becomes aware of the United Irishmen's rebellion on shore -- his father was a United Irishman, and Donal finds himself caught in a conflict of loyalties between his own people and his comrades on the ship of the King's Navy.