In The Duchess of Malfi, a play by John Webster, friends Delio and Antonio are chatting. Antonio has returned from France, where he favored the honest courtiers. Unhappy, sinister Bosola receives gold coins from Duke Ferdinand to spy on the Duchess as the horse manager. Both Ferdinand and his brother, the Cardinal, instruct their sister not to remarry and she obliges. However, she secretly confides with her maid Cariola that she desires to remarry. She proceeds to secretly marry Antonio, her gallant steward.

Bosola gives the Duchess apricots. When she falls ill, Antonio uses the apricots to try to cover up her pregnancy. He announces that she was poisoned by the fruit. Antonio orders the house locked and everyone to their rooms due to a fictitious Swiss burglar who stole the Duchess’s jewels. She secretly gives birth to a baby boy. Ferdinand flies off the handle and wants to kill his sister, her lover, and the baby. The Cardinal slyly plots his next move.

Ferdinand visits his sister. Handing her a knife, he commands her to commit suicide. The Duchess devises a plan to banish Antonio from the palace for stealing. Bosola insists that she is making a mistake, and the trusting Duchess reveals to him her husband's identity. He informs the Duchess’s brother that Antonio is her husband. The Duchess and her family rendezvous at the Shrine and are shocked to discover that they have been banished. Antonio heads toward Milan, while Bosola takes the Duchess back to her palace prison.

The Duchess is led to believe that the wax figures are the dead bodies of her family. She wants to die but Bosola encourages her to live. Ferdinand tries to make his sister become mad by housing madmen in her palace. It has the opposite effect and enables her to be sane. Bosola orders the executioners to strangle her. She submits to death peacefully, while Cariola fights for every last breath. Ferdinand is pleased with the deaths, while Bosola is unnerved. Nevertheless, he seeks his financial reward.

Antonio naively plans to visit the Cardinal during the night. Pesacara and the Doctor are concerned about Ferdinand’s unusual were-wolf behavior. The Cardinal admits to his lover Julia that he plotted his sister’s death. Then, he poisons Julia. He orders Bosola to kill Antonio. The Cardinal makes everyone promise to not leave their rooms during the night, even if they hear strange noises from his brother. He tells them this because he wants to move Julia’s dead body. Due to Bosola’s terrified state of being killed by the Cardinal, he stabs the next person he comes across with in the dark which happens to be Antonio. Antonio dies.

The Cardinal tries to pay off Bosola, but Bosola stabs him. Ferdinand stabs his brother, too, before attacking Bosola. Bosola stabs Ferdinand who dies. The Cardinal is not dead yet when the others enter and demand an explanation. Bosola states that he took revenge for the previous deaths. The Cardinal and Bosola die.

Delio enters with Antonio’s eldest son, and they witness the results of evil acts. Delio wants the remaining men to join together to help raise the boy.