PARIS — It was, yes, a dark and stormy night two centuries ago. Indeed, it was a dark and stormy summer—so dark, so stormy, that those who lived through it remembered 1816 as the year with no summer at all.

But on one long night the horror that 18-year-old Mary Wollstonecraft Godwin confronted was writer’s block.

The would-be author was the daughter of the celebrated and notorious William Godwin, known as the father of philosophical anarchism, and Mary Wollstonecraft, a passionate advocate of women’s rights who had died when little Mary was born.

Now the teenage Mary was vacationing on the shores of Lake Geneva with a group of very talented, famous, freethinking and free-loving friends.

Among them was the poet Lord Byron, 28, who was almost as well known for his womanizing as for his verse. His literate wit and handsome face made him a Romantic idol, his powerful body bespoke all kinds of prowess, and his clubfoot leant him an alluring vulnerability. One former lover called him “mad, bad, and dangerous to know,” which was about right.

It was Byron, in fact, who was the unwitting cause of the blank page tormenting Mary.

Several days earlier, Godwin and another rather more ethereal poet, Percy Bysshe Shelley, who would soon be Mary’s husband, had arrived in Switzerland for a rendezvous with Byron. With them was Mary’s stepsister, Claire Clairmont, who was not quite a year younger.

Byron, who had fled a crumbling marriage and crippling debts, was holed up in a luxurious lakeside property called Villa Diodati, and the young, hedonistic group expected a summer of mountain hikes with a bit of idyllic boating. But weirdly glacial temperatures and frequent storms kept them mostly confined indoors, where long philosophical discussions were rumored to have been accompanied with copious amounts of sex, wine, and laudanum, an opium-laced tonic.

What the debauched wordsmiths didn’t know was that a global climate catastrophe had caused their wintry midsummer.

In 1815, Mount Tambora in what is now Indonesia blew up—the largest volcanic eruption in recorded history. Such enormous quantities of ash particles were blasted into the atmosphere that the earth’s temperature dropped by three degrees Celsius, and many areas of the world suffered an unseasonable chill that lingered for months. Widespread crop failure and food shortages plagued North America, while parts of Europe suffered hibernal storms and frosts.

The origins and extent of the disaster were unknown to Mary Godwin, Byron, and everyone else who shivered through the summer of 1816. What would become known throughout history as “The Year Without a Summer,” was, for this group of revelers just a mysterious spate of supernaturally awful weather.

“One night we enjoyed a finer storm than I had ever before beheld,” Godwin wrote in one of her letters. “The lake was lit up—the pines on Jura made visible and all the scene illuminated for an instant, when a pitchy blackness succeeded, and the thunder came in frightful bursts over our heads amid the darkness.”

As the wind beat against the windows and the rain churned up waves on the lake, the group spent the evening discussing the French translation of a German collection of ghost stories aptly titled Fantasmagoriana. Likely inspired by the sinister ambiance, Byron challenged each of his guests to craft his or her own tale of terror.

“I busied myself to think of a story,” Mary would write years later in the preface to one of the most famous horror novels of all time. “One which would speak to the mysterious fears of our nature, and awaken thrilling horror—one to make the reader dread to look round, to curdle the blood, and quicken the beatings of the heart.” Unfortunately, instead she “felt that blank incapability of invention which is the greatest misery of authorship, when dull Nothing replies to our anxious invocations.”

One night, after listening to Byron and Shelley have a long conversation about scientific experiments and the possibility of reanimating corpses, Mary suffered horrifying visions as she tried to sleep.

She imagined a doctor who had assembled a living thing from pieces of dead bodies: “I saw the pale student of unhallowed arts kneeling beside the thing he had put together,” she wrote. “I saw the hideous phantasm of a man stretched out, and then, on the working of some powerful engine, show signs of life, and stir with an uneasy, half vital motion.”

The nightmare put an end to her writer’s block, and, thanks to the ongoing storms, Mary Shelley, as she would soon be known, began penning the first pages of Frankenstein in the weeks that followed. Two centuries later, the novel is considered a Gothic masterpiece and its monster remains a potent fixture in popular culture, appearing everywhere from films to plays to cereal boxes.

“It is actually the most-read novel in American high schools," Neil Fraistat, a professor of English at the University of Maryland told The Daily Beast. “It might be the most read novel in the world.”

Fraistat, who also acts as the general editor of the Shelley Godwin Archive, which contains digital copies of Mary Shelley’s manuscripts, said he was nonetheless surprised by the worldwide interest the site generated.

“When we launched the archive with the Frankenstein manuscripts, we had 60,000 unique visitors within 24 hours, and disproportionately those visitors were coming from Latin America and Eastern Europe—places that any American scholar had no idea there was that kind of interest.”

Ruth Wylie, the assistant director of the Center for Science and the Imagination at Arizona State University, told The Daily Beast that even though two centuries have passed since Mary Shelley took her pen to the page, her novel remains relevant.

“It’s a phenomenal story that still makes a lot of sense today,” said Wylie, who is involved with the university’s Frankenstein Bicentennial Project. “We don’t have good answers to the questions Shelley poses 200 years ago. We are still trying to figure out how to balance this idea of innovation and ethical responsibility.”

Although Mary Shelley’s macabre creation cemented her place in literary history, a lesser-known member of the group brought an equally enduring monster to life. A fifth addition and something of a fifth wheel in the Villa Diodati crew was John Polidori (unfortunately nicknamed “Polly Dolly”). He had traveled to Geneva with Byron as the poet’s personal physician. Overshadowed by his famous peers, the 21-year-old wannabe writer nonetheless picked up the discarded draft of the story Byron had started on those dark and stormy nights.

Polidori’s creation, The Vampyre, told of the mysterious Lord Ruthven, a suave aristocrat who seduces and murders pretty young things. Prior to Polidori’s Ruthven, vampires were portrayed as ghoulish zombie-like creatures who preyed upon equally unsophisticated European villagers. His smooth and deadly nobleman (thought to be based on Lord Byron) paved the way for modern vampire lore, including Bram Stoker’s iconic Dracula.

Unfortunately for the father of the modern vampire, Polidori suffered rejection on both social and professional fronts.

Byron, having grown irritated with his sensitive young employee and his frequent bouts of ill health, shipped Polidori back to England before the summer on Lake Geneva ended. To add insult to injury, three years after The Vampyre was published, the work was falsely attributed to Byron.

“He was looked at, by Byron especially, as a lesser-than-hanger-on,” said Fraistat. “Polidori was not as famous, not as wealthy, not as connected, and he was ostracized.”

If the disastrous climate drove the party indoors, it was the early stages of a disastrous love affair that brought Mary Godwin and Percy Shelley to Byron’s doorstep in the first place. Before he fled England for Switzerland, Byron had begun sleeping with Mary’s then-17-year-old stepsister, Claire Clairmont, who also is rumored to have had an affair with Shelley.

Having fallen fast and hard for Byron, poetry’s bad boy, Clairmont traveled to Switzerland to seek him out, convincing Mary and Percy to come along. Although Byron was less-than-smitten with Clairmont, he wasn’t about to toss his love-struck young admirer out of bed, either.

“Now, don’t scold, but what could I do?” he wrote in a letter to his half-sister, who (surprise!) was also his lover. “I could not exactly play the Stoic with a woman— who had scrambled eight hundred miles to unphilosophize me.”

In short order, the behavior of Byron and his bohemian cronies raised the hackles of Lake Geneva’s stuffier British visitors.

“Our late great arrival is Lord Byron … and another family of very suspicious appearance,” one English gentleman wrote in a letter home. “How many he has at his disposal out of the whole set I know not, but different houses have been taken for both establishments.”

“He was insolent and repulsive, and his countenance is much disliked,” insisted the man, identified only as J.S.

Even Byron’s good friend Percy Shelley could be put off by his antics.

“Lord Byron, is an exceedingly interesting person,” Shelley wrote in a letter to the novelist Thomas Love Peacock that July. “Is it not to be regretted that he is the slave to the vilest and most vulgar prejudices, and as mad as the winds?”

As the chilly summer wore on, Byron grew increasingly tired of Clairmont and began avoiding her altogether. When she and the rest of the group left Switzerland at the end of August, Byron didn’t even bother to bid his broken-hearted lover good-bye.

Complicating matters was the fact that Clairmont was pregnant with Byron’s child. It was eventually decided that he would look after the baby while allowing Clairmont to visit under the guise of an aunt—an arrangement to which the impoverished young woman reluctantly agreed.

“A mistress never is nor can be a friend,” Byron is quoted as saying. “While you agree, you are lovers; and when it is over, anything but friends.”

Indeed, in the years that followed, Byron and Clairmont’s relationship further deteriorated, with Byron cruelly denying Clairmont access to her daughter.

“I have said before, you may destroy me, torment me, but your power cannot eradicate in my bosom the feelings of nature, made stronger in me by oppression and solitude,” Clairmont wrote in a letter to Byron dated May 4, 1820. “I beg from you the indulgence of a visit from my child.”

However, Byron refused to relent, instead shipping the little girl off to a convent in Italy, where she contracted an illness (possibly typhus or malaria) and died at just five years old.

Despite the suffering Clairmont endured over the affair, it was she who had the last word.

Nearly two centuries after that scandalous summer by the lake, a Cambridge scholar uncovered Clairmont’s unpublished memoir. In the document, an elderly Clairmont calls out Shelley and Byron for “lying, meanness, cruelty, and treachery,” and likens Byron to a “human tiger” who preyed on “defenseless women.” According to Clairmont, the true demons at Villa Diodati were not the fictional creatures on the page, but the Romantic poets themselves.

“Under the influence of the doctrine and belief of free love, I saw the two first poets of England… become monsters,” Clairmont wrote. “By preying on themselves and others, the worshippers of free love turned their existence into perfect hell.”

Whether or not their existence was actually hellish, it was certainly brief.

In the years following their return to England, tragedy stalked members of the Geneva clique. Just five years after the summer at Villa Diodati, Polidori committed suicide in London at the age of 25 by ingesting poison. A year later, Percy Shelley drowned while boating off the coast of Livorno, Italy. Byron died after contracting an unknown illness in Greece in 1824. And prior to her husband’s death, Mary Shelley lost three young children to illness. Decades later, she returned to the Villa Diodati and to her memories of her fateful summer there.

“There were the terraces and vineyards, the upward path threading them, the little port where our boat lay moored,” she wrote of the visit. “I could mark and recognize a thousand slight peculiarities.”

She continued:

“Was I the same person who had lived there, the companion of the dead? For all were gone … storm, and blight, and death, had passed over, and destroyed all.”

What Mary Shelley couldn’t have fathomed is that both the fictional monsters that emerged from the summer of 1816 and the monstrous legends of their creators are, 200 years later, very much alive.