'The Duchess of Malfi' is a tragedy written by:

The Duchess of Malfi, five-act tragedy by English dramatist John Webster, performed 1613/14 and published in 1623.
The Duchess of Malfi tells the story of the spirited duchess and her love for her trustworthy steward Antonio. They marry secretly, despite the opposition of her two brothers, Ferdinand (the Duke of Calabria) and the Cardinal. Although she bears three children, she refuses to name the father.
Source: Britannica.com