"a mystery of Udolpho"

The Mysteries of Udolpho (1794) by Ann Radcliffe is often held up as the archetypal Gothic novel, and it was extremely popular during the 19th century. The plot concerns the misfortunes which befall its heroine, the orphaned Emily St. Aubert, who is imprisoned in the remote and gloomy castle of Udolpho by her villainous uncle, the scheming Montoni. Udolpho’s secret passageways, crumbling turrets and supernatural terrors all colour the governess’s impressions of Bly. The Mysteries of Udolpho is best-known today for the spoofing it receives at the hands of Jane Austen in Northanger Abbey (a.1817).