It’s been more than four centuries since 12 men and women were put on trial after being accused of witchcraft in the Lancashire district of Pendle Hill. One died in prison and one was judged innocent, but 10 more were found guilty and hanged until dead. Yet no matter how horrifying, the tale fascinates us to this day.

In fact, it sometimes feels like witches have gone completely mainstream – from Wicked, the musical, recently adapted into a hit Hollywood film, to the Harry Potter TV series due next year. Social media, meanwhile, is a coven of its own, with #WitchTok gaining more than 52 billion views. Even supermarkets have got in on the act, selling spell books and duvets patterned with the sort of symbolism that, in the 1980s, might have led to a door knock by a police officer. But once you start to delve into the details, as I’ve done for my book about the Pendle Witch Trials, you begin to understand why the story keeps us spellbound – and why witches make such a perennially entertaining subject in popular culture.

A heady concoction of the unutterably strange and the distinctly relatable makes it impossible to forget. The real horrors, of course, are not supernatural, but those inflicted upon folk whose lives were already more difficult than we could ever fathom.

Remember, as you read, that these events took place in a world where light came only from fire and sky; where there was no medical profession as such, science remained largely in its infancy; and the printing press was still a relatively new invention, leaving people largely ignorant of life beyond their own surroundings.

The Pendle case, which would resulted in 11 judicial deaths, began with a small incident typical of the cause of many witch trials: a squabble. In this case, the two participants were unknown to each other until they met on a path near Colne in March 1612. The official story (the reality is far more complex, but these events led to the trial of 1612) is this: 17-year-old Alizon Device was on her way to Trawden to spend the day begging, when she met a middle-aged peddler named John Law.

Alizon either asked or demanded to have some pins from the pack of goods Law carried. Pins then were expensive items, handcrafted and used frequently in love magic and divination. Law refused to let Alizon have any pins and she began to berate him.

As the peddler went to continue his journey, a black dog appeared out of nowhere and spoke to Alizon, asking what she might have him do to the peddler. “Lame him,” Alizon retorted, seemingly unperturbed by the talking dog.

She was aghast, however, when the peddler suddenly fell to the ground, immobile. The black dog vanished and so, too, did Alizon – apparently running off while Law eventually made it to a nearby ale house.

Bed-bound by what we would now recognise as the symptoms of a stroke, he managed to send word to his son, clothier Abraham Law in Halifax, that he had been bewitched. Abraham arrived and immediately began searching for Alizon. He soon found her, for she belonged to one of the most notorious families in the area.

She accompanied him to the ale house and begged his father’s forgiveness, weeping. The older man accepted her apology. Unfortunately for Alizon, Abraham Law was far less benevolent. He visited the local magistrate, Roger Nowell, and insisted that he should investigate further. Although often cast as the villain of the piece, wealthy and well-connected Nowell had no choice but to pursue the matter once he had been approached by the peddler’s son.

Hauled in for questioning, Alizon not only confessed to deliberately laming John Law, but declared that her grandmother was a witch, and went on to implicate another woman of murder by witchcraft.

Nowell, for his part, was already acquainted with the two warring families at the heart of the matter. Both were headed by fiercely independent widows in their seventies: Alizon’s grandmother Elizabeth Southerns (known as Demdike) and her former close friend, now enemy, Anne Whittle (nicknamed Chattox).

The exact source of the matriarchs’ dispute is unknown, but each wanted to be regarded as the best “cunning” woman in the neighbourhood. Cunning folk – for there were men as well as women – were an important part of most communities, especially those as rural as Pendle.

They were not witches per se but were believed to have special powers which they used to good effect – curing illnesses, finding lost or stolen property and interfering in romances. Few were paid with money because food, drink and other basic necessities were common currency.

But cunning folk could sometimes fall foul of those they were asked to help. If a cow they were brought in to cure languished or died instead, they might be accused of witchcraft. No one wanted that laid at their door as witches were the world’s scourge, viewed as the devil’s servants on earth, there to overthrow all that was good and godly.

King James himself had written a book on these beings (Demonology) and had a keen personal interest, since witches were believed to have tried to scupper the ship carrying his then wife-to-be from Denmark, and later his own fleet, by raising storms.

The two families in Pendle were already on extremely shaky ground, for there had been rumours about their unearthly gifts for years. Questioned by Nowell and a fellow magistrate, they all turned on each other in desperation, confirming some of these suspicions. Consequently, Alizon, Demdike, Chattox and her daughter Anne were dispatched to Lancaster Castle Gaol to await trial at the assize courts, which then took place twice yearly.

Friends and relatives of those left behind subsequently met at Demdike’s old home of Malkin Tower on Good Friday 1612 to discuss what they might do to assist their loved ones. A suggestion made in the heat of the moment – to kill the jailer, blow up the castle with gunpowder and free the prisoners – reached Nowell’s ears.

The entire case exploded. The meeting at Malkin Tower became a witches’ sabbath and the king was told that another pernicious Gunpowder Plot was afoot, similar to the one that had been discovered a few years earlier, in 1605.

Further arrests were made among those who had attended the infamous Malkin Tower meeting, including Alizon’s mother and brother. They joined those already suffering in the underground cells at Lancaster Castle. Conditions were so appalling and mistreatment so rife that Demdike did not survive to stand trial; she died in late May 1612. On August 18, amid great pomp and ceremony, the assizes opened and the first witnesses were heard. But none caused as great a sensation as the testimony given by Alizon’s sister, young Jennet Device. Although she was 11 rather than nine as is usually stated, Jennet nonetheless gave damning evidence against her entire family.

Jennet’s mother was so distraught that she was removed from the courtroom while Jennet gave her evidence, standing on a table so that everyone could see her.

No doubt Roger Nowell had some role in Jennet’s betrayal of her family; she was a witness unlike any other and it was her part in the Pendle trial that would directly influence another, held 80 years later, across the Atlantic: Salem. At the end of proceedings, nine people were condemned to death: Alizon, her mother Elizabeth, and brother James; Chattox and her daughter Anne; and family friends Alice Nutter, Katherine Hewitt, and mother and son Jane and John Bulcock.

Contrary to popular belief, very few of those destined to die as witches in England and Wales were burned at the stake – the chosen method of execution in Scotland and on the Continent. Most were hanged, including one woman who had attended the Good Friday meeting, Jennet Preston, who was already dead at the time of the Pendle trial.

Having lived in Gisburn, which was then in Yorkshire, she was tried in York and met her death in July on the gallows that stood on what is now York Racecourse. The Pendle witches were hanged on Gallows Hill in Lancaster on August 20, 1612. An account of the case was written by the clerk of court, Thomas Potts. He dedicated his book to the man who raised him, Thomas Knyvett.

History remembers Knyvett as a favourite of the king, due to his arrest of Guy Fawkes below the Houses of Parliament on November 5, 1605.

A little over 200 years after the Lancaster hangings, author William Harrison Ainsworth – dubbed “the Northern Dickens” – wrote The Lancashire Witches, a Gothic novel based on the case. It was an immediate bestseller. Much of what we think we know about the Pendle witches is actually fiction, as a result of Ainsworth’s book.

It could also be seen as the inspiration for countless other accounts, both fiction and non-fiction, and much of the folklore surrounding witches that has been passed down in popular culture through films and fairy-tales.

Today, witches have lost much of their terror, demystified by Disney and youngsters in costume for Halloween. But these were real men and women. And one of my reasons for wanting to write about the case is to tell, as far as possible, the true story of the women and men whose deaths are such a part of Lancashire folklore. There are witches everywhere you look in Pendle: on buses, on beermats, on pub signs, on way markers, on estate agency boards… the list is endless.

However, the real people behind the cartoonish imagery are elusive, although that hasn’t stopped busloads of tourists heading to the region year after year… including me – from my first visit as a young mum years ago, to many, many more trips while researching this book.

A couple of Halloweens ago, my partner and I rented a holiday cottage at the very foot of Pendle Hill. After dark, we could see little lights bobbing about the winding path to the summit as walkers headed upwards.

In the old days, there was a tradition known as “leeting” the witches, whereby you carried a burning candle up the hill and if the flame remained lit, the witches would leave you in peace for another year. Those whose candles sputtered out were doomed.

Today’s habit of heading to the top with a torch seems safer all round.

• Something Wicked: The Lives, Crimes and Deaths of the Pendle Witches, by Carol Ann Lee (John Blake, £20) is out now.

Her previous book on Ruth Ellis, A Fine Day for a Hanging, is the basis for drama A Cruel Love, due on ITV later this month