Read more: A love of desolation and ruins

Around two hundred years ago, in May 1816, a small group of English travellers checked into the Hotel d’Angleterre, a large three-storey stone building facing the Alps on the north side of Lake Geneva. In the group was the 23-year-old poet Percy Shelley, his mistress, Mary Wollstonecraft Godwin, still only 18 years old, and their four-month-old son William. (Mary was to marry Percy in December that year, just two weeks after hearing about the suicide of his abandoned wife Harriet.) The final member of the company was Mary’s step-sister Clare Clairmont, eight months her junior—“the type of young woman who today would be known as ‘arty,’” in Muriel Spark’s tart summary.

Exhausted after ten days of travel from London, during which Mary had suffered terribly from travel sickness, the friends were more like refugees than tourists. Shelley had been so tormented by emotional and financial difficulties that he had become dangerously ill. Mary was troubled by memories and dreams about the loss of her baby girl, who was born prematurely in February 1815 and died shortly after. A few weeks earlier, Clare Clairmont had set her cap at Lord Byron, who found her annoying but had sex with her anyway. It was Claire who had suggested that they should rendezvous with Byron in Geneva, and it’s possible that Shelley agreed with her plans partly because he wanted to meet the older poet.

Byron had also fled London in February, expecting at any moment to be arrested by bailiffs. He brought along his new personal physician John Polidori, who had qualified as a doctor the year before, at the precocious age of 19. Unknown to Byron, Polidori was also something of a spy: Byron’s publisher, John Murray, had slipped him £500 to keep a diary of his employer’s adventures, which might form the basis of a racy best-seller.

Shelley and Byron were both a little shy on their first meeting by the lakeside, but an agreeable dinner soon thawed them and established that they had a good deal in common. Soon, they were all but inseparable, and joined in spells of speculative talk from which Mary, to her surprise and dismay, was often excluded.

By now, the management of the Hotel d’Angleterre had grown alarmed by the potential for scandal from these mad English folk, and it was time to find a new place to stay. Byron discovered two nearby properties—a large porticoed house called the Villa Diodati, and, a few minutes’ walk away, a small chalet. Byron and his entourage took the former, and the Shelley group the latter, though a spell of bad weather soon forced everyone into the Villa. Some 15 years later, Mary Shelley wrote of their stay: “it proved a wet, ungenial summer, and incessant rain often confined us for days to the house. Some volumes of ghost stories translated from the German into French, fell into our hands.” This gave rise to an idea. “’We will each write a ghost story’ said Lord Byron; and his proposition was acceded to.

Oddly, the two established writers proved less apt for the task than the two novices. Shelley tried to write something inspired by his childhood, but soon gave up; Byron wrote a short, fragmentary vampire tale, later published but not much read, then or now. Mary recalled that “Poor Polidori had some terrible idea about a skull-headed lady”; this was so, but Polidori was working a more enduring story, too.

At first, Mary found herself stumped. She could not think of anything spooky enough to be worth turning into a tale. Instead, she listened to the two poets talk about ghosts and vampires, and the principle of life, and whether galvanism might—as seemed likely—be able to reanimate dead tissues. And then, finally, she suffered a night of insomnia. On the evening of the 17th, or possibly the 18th June (her diary is ambiguous), she read out the first passage of a strange fiction to her friends. It began:

“It was on a dreary night of November, that I beheld my man completed and with an anxiety that almost amounted to agony, I collected instruments of life about me, and endeavoured to infuse a spark of being into the lifeless thing that lay at my feet….”

This was, of course, the first stirrings of the novel she would later call her “hideous progeny”—Frankenstein; or, the Modern Prometheus. In those same days, Claire felt stirrings of her own: she was pregnant with a child that Byron, despite his resentment (“Is the brat mine?) was soon obliged to acknowledge, since the only other possible father was Shelley, whose word and conduct he trusted.

And Polidori? After some bitter arguments with both poets, which almost came to a duel, he went off in a sulk and, taking his inspiration from Byron’s effort, started work on a short novel, The Vampyre. On its publication in 1819, readers noted how closely its villain, Lord Ruthven, resembled another well-known lord. Some took the tale as an accurate account of Byron’s wicked adventures; others, especially in France, that it was not merely by Byron himself but one of his finest works. It became an international bestseller and established the notion of the vampire as a suave aristocrat rather than a smelly, slobbering peasant. It was this image that Bram Stoker had in mind some 70 years later, when he wrote Dracula.

We owe the two greatest horror tales of the last two centuries to a handful of troubled souls shut up together in an old house one wet summer. Within eight years, all the men who had taken part in the competition were dead: Polidori most likely of suicide; Shelley by drowning, after his yacht Ariel sank in a storm off the northwest coast of Italy; and Byron of illness contracted during his adventures in the cause of Greek freedom.

Mary Shelley lived on until 1851—the year of the Great Exhibition, a celebration of the wonderful, rather than the satanic potential of science and technology. A few years earlier, she had re-visited the Villa Diodati, and fell to musing. She glumly regarded herself as “the companion of the dead… For all were gone: even my young child… storm, and blight, and death, had passed over, and destroyed all.” One can only hope that she foresaw how remarkably her “progeny” would survive into the 21st century. Mary Shelley’s intelligence and literary talent is plain to see in other writings, but it took an emotionally charged house party to sting her into genius, and literary immortality.