Ann Radcliffe (http://en.wikipedia.org/wiki/Ann_Radcliffe) published this very early horror/thriller in 1794, establishing the popularity of the Gothic.
Beautiful young heiress Emily St. Aubert is frightened when she finds herself orphaned and in the hands of her cold and distant aunt, Madame Cheron. But her fear turns to terror when Madame Cheron agrees to marry the haughty and brooding Signor Montoni, and she finds herself trapped in the castle Udolpho. She is threatened by Montoni’s terrible greed and haunted by the secrets of the medieval fortress.
Will Emily find the strength to survive this place of nightmares and get back to her native Gascony? Her sentimental lover Valancourt awaits. Or will Montoni and his wicked schemes destroy her completely? This is an extremely slow burn Romantic thriller and charms more than it horrifies the modern reader. It remains, however, the locus classicus for the genre.
880 pages in Penguin paperback edition.
ISBN 978-0141191935
Ann Radcliffe