Mystery? Check. Malevolent villain? Check. Quasi-supernatural events, like meteors and bloody markings of uncertain origin? Also check. There may not be a castle or ghost, but we're definitely in familiar Gothic territory here.
For all the supernatural elements, The Scarlet Letter also explores the life and times of early America. It may not be 100% accurate, but it's a historical novel set in a real place among real people, like Governor Bellingham and Mistress Hibbins. We learn about early American crime and punishment; we learn about their attitudes toward meteors and other natural phenomena; we learn what they wore and how they acted; and we also learn how they thought about their little community.
Finally, The Scarlet Letter is a love story. Surprised? No, there's no bodice-ribbing, but Pearl is the physical manifestation of a passionate love affair, and the story ends by making Hester into a kind of prophetess suggesting that marriages of convenience aren't so convenient after all: that "in Heaven's own time, a new truth would be revealed, in order to establish the whole relation between man and woman on a surer ground of mutual happiness" (24.11). In other words, people will begin to marry for love.
Crazy idea, right?