Sexual arousal was never far below the surface during the religious ecstasies of medieval mystics, but as the Catholic church controlled education few people questioned mystical experience as being anything but a pathway to the divine.

English author Catherine Chanter, who was raised an Anglican, researched the practices of the medieval mystics for The Well, her suspenseful debut novel about an English couple, Ruth and Mark Ardingly, who settle on a farm as an unprecedented drought grips Britain. The Ardinglys' home becomes known as "The Well"  because it is the only place in the country that receives rain. The story is told in the first person by Ruth, who has been jailed for arson and the suspected murder of her grandson, Lucien.

Dealing with the disintegration of her family and the ire of the community who resent the farm's prosperity, Ruth finds herself a curiosity of journalists, nut-jobs and hippies as well as a group of misandristic Catholic nuns called the Sisters of the Rose, who try to convince her she is a Messiah. Ecstasies are in their religious armoury.

Chanter, 56, was staying near the Welsh border in a cottage that lacked mains water when she came up with the idea for The Well several years ago. It was a long hot summer and she relied on water pumped from a well. At the time she was also reading about the concept of the Annunciation, when Mary is told by the angel Gabriel she will be the mother of God. "I thought that's an interesting idea," she says. "What happens when you are a 'chosen' woman in contemporary Britain?"

Chanter, who lives in Oxford with her husband and has three grown-up children, has a strong affinity for the countryside, having being raised in the West Country near Devon, and counts Thomas Hardy's novels among her strongest literary influences. After studying literature at Oxford she worked as a lobbyist in Britain and the US but later retrained as a teacher of children with mental health problems. She has since had poetry published as well as a collection of short stories, Rooms of the Mind, which sprang from her work dealing with disturbed children.

Last year The Well won Cambridge University's Lucy Cavendish Prize, a competition for unpublished female authors over the age of 21. The novel deals with identity and the ability to keep ourselves together during a crisis. Told in time-shifts, it builds a portrait of a woman shaped by tragedy and extraordinary circumstance, and shows how mental fragility can be at the mercy of vulnerability.

Societies always have had changing views of what defines insanity, Chanter says. "For The Well, I was interested in a group, primarily women, in medieval England who formed the mystics, such as Julian of Norwich ... I have been interested in their writing and this line between religious ecstasy, sexual orgasm and the relationship with Christ. Nowadays they would be treated with antipsychotic drugs and be considered mad."

Also part of Chanter's research were modern nuns and "the whole weird world" of online worship. "Some are honourable and bring genuine faith to people," she says, "but others are incredibly predatory and want your personal details, and you click on a candle and it costs $10."

Chanter, who was adopted, says her birth mother, with whom she has only recently made contact, became a Buddhist after rejecting Catholicism. "Interestingly, that was one of the few stipulations my birth mother made when she gave me up for adoption – a scribbled note in the file saying, 'Mother requests Protestant family' ".

As to whether she considers herself religious, Chanter says she is not "a fully paid-up member of any creed". However, she remains interested in the exploration of the spiritual life: "I always think that if I ever get to the pearly gates and there is someone there, I can at least say to them I tried."