Voller reveals in Part 1 the way in which the psychological and narrative structures of the sublime, as elaborated by Edmund Burke and his contemporaries, gave Gothic fictions much of their characteristic shape and tone. He defines the Gothic mode in close readings of works by Radcliffe, Reeve, Lewis, and Brown.

The Supernatural Sublime breaks new ground by establishing a classification schema for Gothic fictions, an anatomy based on the underlying structure of the sublime experience and its powerful influence on what can be called the metaphysical implications of Gothic supernaturalism.

In Part 2, Voller extends his examination of supernatural sublimity into the works of major Romantic authors on both sides of the Atlantic. He demonstrates that, while authors such as Coleridge, the Shelleys, Byron, Hawthorne, and Poe were familiar with Gothic supernaturalism, their use of the supernatural is not an adoption of Gothic conventions but a sophisticated critique of them.

Influenced by Kant's idealist interpretation of sublimity, and rejecting what they understood to be the histrionic excesses of Gothic fiction, the Romantics elaborated a more psychologically astute and intellectually subtle supernaturalism that served as a foundation for later nineteenth-century supernaturalism.