The Castle of Otranto by Horace Walpole

A haunted castle, secret passages, a villain, a damsel in distress, an unwanted wife and a hero with a shrouded past: all the vital ingredients for a gothic novel - in the case of The Castle of Otranto (1764), the first gothic novel.

Conrad is heir to the lands of Otranto; unfortunately, he dies under very odd and inexplicable circumstances on his wedding day.  Isabella, his betrothed, has been spared marriage to a sickly young man.  Lord Manfred, Conrad's father, desperate for an heir, hatches a monstrous plot to marry Isabella himself.  What follows is a desperate game of hide and seek.  Can anyone save Isabella from Manfred's clutches?

The basic conceit of this novel is contained in the preface to the first edition.  Supposedly, the book is a translation  of an Italian manuscript dated 1529 that was found in a private library somewhere in the north of England.  

The first edition was well received by the public.  Walpole caused a bit of an uproar by revealing in the preface to the second edition there had been no manuscript and that the work was entirely from his own imagination.  In this preface he makes clear his artistic intentions:

It was an attempt to blend ... two kinds of romance, the ancient and the modern. In the former all was imagination and improbability: in the latter, nature is always intended to be, and sometimes has been, copied with success.

In other words, Walpole was trying to tell a tale of the supernatural using a realistic narrative style.  He succeeded.  

One can understand the popularity of the novel amongst its contemporary readers and those in the following generations.  Indeed, it spawned its own genre - the gothic novel - and there have been many imitators and innovators.  We are still telling gothic tales in modern times: The Name of the Rose, Umberto Eco's popular novel of the 1980's, adopts Walpole's premise of a mediaeval Italian manuscript coming to light and being translated; Ridley Scott's Alien is a gothic tale set in outer space.

It has been 250 years since The Castle of Otranto was first published.  This presents a problem for the modern reader: we know these gothic tropes so well it is hard for the work to seem fresh and new.  From our perspective it is, perhaps, the unravelling of the supernatural mystery at the heart of the tale that presents the greatest interest.