There is nothing very new in the plot, which has all the stock properties of romantic fiction, as common in the days of Sidney’s “Arcadia” as in those of Sylvanus Cobb.  Alfonso, the former lord of Otranto, had been poisoned in Palestine by his chamberlain Ricardo, who forged a will making himself Alfonso’s heir.  To make his peace with God, the usurper founded a church and two convents in honor of St. Nicholas, who “appeared to him in a dream and promised that Ricardo’s posterity should reign in Otranto until the rightful owner should be grown too large to inhabit the castle.”  When the story opens, this prophecy is about to be fulfilled.  The tyrant Manfred, grandson of the usurper, is on the point of celebrating the marriage of his only son, when the youth is crushed to death by a colossal helmet that drops, from nobody knows where, into the courtyard of the castle.  Gigantic armor haunts the castle piecemeal:  a monstrous gauntlet is laid upon the banister of the great staircase; a mailed foot appears in one apartment; a sword is brought into the courtyard on the shoulders of a hundred men.  And finally the proprietor of these fragmentary apparitions, in “the form of Alfonso, dilated to an immense magnitude,” throws down the walls of the castle, pronounces the words “Behold in Theodore the true heir of Alfonso,” and with a clap of thunder ascends to heaven.  Theodore is, of course, the young peasant, grandson of the crusader by a fair Sicilian secretly espoused en route for the Holy Land; and he is identified by the strawberry mark of old romance, in this instance the figure of a bloody arrow impressed upon his shoulder.  There are other supernatural portents, such as a skeleton with a cowl and a hollow voice, a portrait which descends from its panel, and a statue that bleeds at the nose.

The novel feature in the “Castle of Otranto” was its Gothic setting; the “wind whistling through the battlements”; the secret trap-door, with iron ring, by which Isabella sought to make her escape.  “An awful silence reigned throughout those subterraneous regions, except now and then some blasts of wind that shook the doors she had passed, and which, grating on the rusty hinges, were re-echoed through that long labyrinth of darkness.  The wind extinguished her candle, but an imperfect ray of clouded moonshine gleamed through a cranny in the roof of the vault and fell directly on the spring of the trap-door.”  But Walpole’s medievalism was very thin.  He took some pains with the description of the feudal cavalcade entering the castle gate with the great sword, but the passage is incorrect and poor in detail compared with similar things in Scott.  The book was not an historical romance, and the manners, sentiments, language, all were modern.  Walpole knew little about the Middle Ages and was not in touch with their spirit.  At bottom he was a trifler, a fribble; and his incurable superficiality, dilettantism, and want of seriousness, made all his real cleverness of no avail when applied to such a subject as “The Castle of Otranto."[14]