In collaboration with a Scotland Yard detective, who is also a Freemason, Frances Yates, eminent historian of Renaissance spirituality and proponent of martyred priest Giordano Bruno, employs her unique scholarship to solve a murder and the theft of a rare volume in the renowned musty library of ancient philosophical traditions, where she has long been a resident scholar.

While immersed in an article regarding the significance of mysterious tarot cards, Yates comes to realize that the recurring images of the cards illustrate universal life stages and character traits that may provide clues to the identity of the murderer. Along the way, she encounters more recent scholarship regarding feminist theology that, together with the tarot, prompts her to reconsider her own patriarchal spiritual worldview.