Her 1962 novel "Devil Water" concerns James, the luckless Earl of Derwentwater and his involvement with the Jacobite rising of 1715. She also narrates the story of his brother Charles, beheaded after the 1745 rebellion, the last man to die for the cause. The action of the novel moves back and forth between Northumberland, Tyneside, London, and the United States. Seton stated that the book developed out of her love for Northumberland. She certainly visited her Snowdon cousins at Felton. Billy Pigg, the celebrated Northumbrian piper played "Derwentwater's Farewell" especially for her. The novel shows her typical thorough research of events and places, though the accents are a little wayward. Seton said that her greatest debt of all was to Miss Amy Flagg of Westoe Village in South Shields, her father's birthplace.