‘Their limbs wracked and, tormented so ... their arms, necks, and backs turned this way and that way, and returned back again. Their mouths stopped, their throats choked. They had several sore fits.’ – A contemporary description of cousins Betty Parris and Abigail Williams, the first of the afflicted at Salem.

Their speech was garbled and their limbs contorted, they wailed and howled and convulsed. It was 1692. Betty was nine and Abigail was 11.

Reverend Samuel Parris was advised by a doctor that the girls, his daughter and niece, respectively, were bewitched. Soon, at least five other girls in Salem Village developed similar symptoms and began to accuse locals of witchcraft including Tituba, a slave, and Sarah Good, a homeless beggar. A flurry of accusations followed, with residents piling on to denounce over 200 people. “Persons of ill-repute” and dedicated churchgoers alike were imprisoned and Bridget Bishop, “known for her gossipy habits and promiscuity”, was the first to be hanged on 10 June. Twenty people were put to death in total with several others dying in prison.

What caused those strange symptoms in Betty, Abigail, and their friends over three centuries ago, and ultimately led to all those deaths?