The history of the Grail legend begins with a romance composed by Chretien de Troyes in the last decades of the twelfth century, Perceval ou Le Conte du Graal. Whereas Chretien's earlier romances explored the secular tensions generated by chivalric and courtly life, the Conte du Graal has appeared to most scholars to resolve such tensions by offering a spiritualized ideal of a new kind of chivalry governed by a universal vision of chivalry's redemptive mission in the world.

Focusing on this earliest extant version of the Grail legend the author proposes instead a social interpretation of Chretien's romance as a story concerned with earthly violence and vendetta. She asserts that, rather than anticipating the mystical quest for the "Holy Grail" narrated in subsequent renditions of the legend, Chretien's Conte du Graal functions as a chronicle of aggressive pursuits at whose core is a long-standing dispute between two principal forces: King Arthur and the Grail lineage.

The author shows how this history of rivalry is revealed through a double narrative that consists of the parallel adventures of Perceval, the heir presumptive of the Grail lineage, and of Gauvain, King Arthur's most powerful and honored champion. In Cazelles's view, the Conte du Graal forecasts a lethal encounter between its two protagonists and points to the presence of a cycle of conflicts and tensions that threatens to engulf the entire chivalric community, including King Arthur himself.

The Unholy Grail assesses the importance of the Conte du Graal as both a crepuscular account of Arthur's "history" and as a final phase of traditional chivalric romance.

It also suggests that the aggressiveness of knightly society as depicted in the Conte du Graal reflects, via a displacement to the imaginary, the very predicament that the chivalric aristocracy - notably the noble sponsors of courtly literature - faced as a result of their declining status during a particularly turbulent period in the history of European feudalism.