The Harrowing of Gwynedd unravels a mesmerizing tapestry of high fantasy, with three commanding figures at its heart. Among them shines Evaine MacRorie, Camber's last living daughter, who once delved into the arcane and intellectual realms alongside her father. Her presence graced the preceding trilogy, yet little was known of her inner workings or aspirations. In this tale, however, she steps boldly into the spotlight. With the absence of formidable giants like Camber, King Cinhil, and her husband Rhys Thuryn, the remaining Deryni turn their eyes to Evaine for guidance and leadership. She emerges as an extraordinary leader, weaving her adept understanding of political tides to unite a diverse and occasionally unpredictable cadre of Deryni nobles. Simultaneously, she alone is equipped to unearth the esoteric and forbidden mystical knowledge that may bring peace to her father's soul. Balancing these myriad responsibilities, she also nurtures and educates her three young children. Evaine faces her sorrow and spiritual doubts in solitude, fearful that sharing her burdens might sow discouragement among her followers.

Through nine previous Deryni novels, Kurtz rarely plunged into the depths of her female characters, even when their deeds propelled the narrative forward. Thus, the prominence of Evaine and the intricate layers of her persona in this book offer an unexpected delight. Significantly, in a genre replete with adolescent quest seekers and warrior women, Evaine MacRorie distinguishes herself. She is a widow and a mother, mastering her scholarly and magical prowess to enact change through her social and spiritual achievements, rather than the clashing of swords.

The narrative's second vital figure is Queron Kinevan, a former Gabrielite brother with a gift for Healing. Previously, Queron made fleeting appearances as the founder of a nascent order—the Servants of Saint Camber. His fervor for this venture once proved irksome to the MacRorie clan, who, aware of Camber's true fate and uneasy with his hastily bestowed sainthood, sought to diminish Queron's crusade without casting aspersions on his devotion.

In the wake of Camber's assassination and the looming threat over the Deryni, Evaine and her brother reassess Queron's importance. A compact and sinewy man, unwavering in his allegiance to Camberite principles, he emerges as a chief strategist in rescuing imperiled Deryni from persecution. When entrusted with Camber's secret identity by the inner circle, Queron's faith wavers but does not shatter. He becomes a paragon of how trust and accountability refine the judgment of someone once impetuous.

Prince Javan, the third central figure, stands second in line for the throne, arriving in the world mere moments after his twin, Alroy. Initially a bewildered boy caught in a web of confusion, Javan embarks on a journey of mastery over his partial Deryni powers. He learns to navigate the treacherous waters of Council politics, discerning true intentions and employing subtle cunning to protect himself and remain connected with his allies. With Alroy's frailty and naivety rendering him a mere puppet of unscrupulous power brokers, Javan will likely need every ounce of his newfound abilities. Despite the precariousness of his position, he retains a buoyant spirit and an earnest honesty, making him a captivating young protagonist.

The cast swells with other notable figures, such as Evaine's brother, Father Joram MacRorie, and Revan, an unconventional evangelist whose second baptism ritual offers a shield and salvation to many endangered Deryni. The stage teems with nobles and religious figures, both virtuous and villainous. Though occasionally a once-distrusted character may prove benevolent and supportive, Kurtz predominantly populates her stories with distinctly drawn heroes and villains.