The "custom of the castle" imposes strange ordeals on knights and ladies seeking hospitality - daunting, mostly evil challenges that travelers must obey or even defend. This seemingly fantastic motif, first conceived by Chretien de Troyes in the twelfth century and widely imitated in medieval French romance, flowered again when Italian and English authors adopted it during the century before Shakespeare's plays and the rise of the novel.

Unlike other scholars who have dismissed it as pure literary convention, Charles Ross finds serious social purpose behind the custom of the castle. Ross explores the changing legal and cultural conceptions of custom in France, Italy, and England to uncover a broad array of moral issues in the many castle stories, where others have seen no more than a fanciful heroic test or an expression of courtly ideology.