My Enemy the Queen — Victoria Holt

Lettice Devereux was beautiful, sophisticated, and impetuous... And she was used to getting her way. Her unbridled passions were exceeded only by her scheming mind. Lettice married the Earl of Leicester, stealing him away from another woman. And Lettice was the mother of the Earl of Essex, who would one day break that same woman's heart. It was Lettice who was the constant figure in a love triangle. And who was the woman she constantly thwarted? None other than Elizabeth I, the great Queen of England....