Set in 17th-century Spain and narrated with hypnotic intensity, Poison is the story of two women, born on the same day, whose lives run a parallel, tragic course. The terror of Spain's Inquisition, the tyranny of superstition, the rapture of religious fervor and the intrigue of the king's court form the backdrop of this rich, mesmerizing novel. 

Francisca de Luarca is the daughter of a poor Castilian silk farmer and shares his passionate determination and imagination. Forbidden by Spanish law to wear the silk her family makes, she dreams of the splendid silk garments woven for kings and queens, even as she fantasizes of learning to read the writing of the saints and becoming like the angels. At the same time, the lovely, naive Marie Louise de Bourbon dances in silk slippers in the Parisian palace of her uncle, King Louis XIV, and imagines her own enchanted future. 

It is in Madrid that the lives of these two young women unfold in tandem, almost touching. Each hoards the memory of her adored lost mother like an amulet. Forced to marry the impotent King Carlos II of Spain, Marie Louise pays dearly for her failure to produce an heir to the throne. And in the tunnels below the city streets, where the hooded torturers of the Grand Inquisitor exact confessions from suspected witches and heretics, Francisca learns the terrible consequences of her obsession with a Catholic priest, the man who teaches her to read and to love.