[2] It dramatizes the life and murder of Inês de Castro, the lover and posthumously recognized wife of King Peter I of Portugal.
Agnes tries to leave Coimbra, but Constantina and Pedro convince her to stay.
Constantina, Pedro and Agnes try to preserve their friendship and love for each other, but struggle with their divided affections.
After her death, Pedro takes his revenge by embarking on a war against his father.
Behn's translation was an inspiration for Catharine Trotter's tragedy of the same name, performed at the Theatre Royal in 1695 with great success.