Professor Michael Padovic is working on a thesis to prove that Shakespeare was of Spanish, not British, ancestry. He and his wife, Helene, travel from their home in Paris to the ancient convent of Arrabida, on the Portuguese coast, where the professor suspects certain essential documents are stored. Their host at the convent is the unsettling guardian, Baltar. Baltar is captivated by the mysterious Helene, and suggests that the professor employ the convent's new archivest, Piedade, as his assistant, so as to divert the professor's attentions from Helene. Baltar's plotting, and Helene's own subtle manipulation, makes the tense situation increasingly bizarre, culminating in a chilling conclusion.