An architect arrives in the decaying town of Cullerne to oversee the restoration of a crumbling cathedral, only to find himself entangled in a long-standing mystery surrounding the local aristocratic family.

Edward Westray, a young and ambitious architect, accepts the commission to repair the ancient church of Cullerne, a task that forces him to confront the town's insular traditions and the secrets of the Blandamer family. He faces opposition from local residents who guard their history with suspicion and hostility, while the physical decay of the cathedral mirrors the moral and financial decline of the local nobility. The narrative unfolds through a measured, descriptive prose style that emphasizes the weight of history on the present, utilizing a third-person perspective to observe the intersection of professional duty and ancestral intrigue.

Readers and critics frequently highlight the novel's exceptional command of atmosphere and its meticulous attention to architectural detail. Discussion often centers on the author's ability to imbue inanimate objects, such as the titular coat of arms, with a sense of foreboding and historical weight. While some readers note the deliberate, unhurried pacing, others appreciate the depth of characterization and the authentic portrayal of early twentieth-century rural life. The work is often cited for its unique blend of mystery and antiquarian interest, making it a distinct entry in the gothic tradition.