Mary Cavanagh's first novel The Crowded Bed is a skilfully complex, psychological piece full of high drama and murky secrets, although at its heart is a loving, long-enduring relationship. It begins with Jewish GP Joe Fortune murdering his father-in-law Gordon before he returns to bed with his sedated wife Anna. Shocking and horrific, you might think, but by the end of the book, one empathises very much with Joe's dark deed because wealthy, powerful, well-connected Gordon is truly a monster.

The book, which is mainly told from Joe's viewpoint, starts five days before the murder and alternates between past and present. Over its course we go through Joe's loving, but suffocating childhood, Oxford university days and his hellish first marriage to a nice Jewish girl. This is interspersed with Anna's loveless upbringing and difficult first marriage. It is clear that they are passionately in love with each other, but that their bed is full of the ghosts of a sometimes unbearable past and Joe wants to murder Gordon in part to avenge these.

When I asked Mary what inspired her to create Joe, she explained how her central character was originally Gordon, but that when Joe appeared, he demanded centre stage.

"He became so fascinating to me," she said. Mary then went through some happy years finding out about Jewish culture. "I tagged on to the shirt-tails of every Jew I knew and made sure that my research was right," she said.

"I went through a phase of being absolutely fascinated with the religion, the people, with the attitude to their faith and their attitudes towards their social structure and culture, which is so much part of Judaism."

Such absorption has enriched the book greatly and some reviewers have said how well she describes Jewish family life. They have also compared her book to such diverse authors as Susan Hill, Anita Shreve, Virginia Woolf and Henry Fielding. Blog reviewers, who are becoming increasingly influential, particularly seem to like her book.

Apart from murder, she tackles some very dark themes: incest, adultery and abuse, but because of the way she writes, they never seem melodramatic. They just unfold, are explained and become part of Anna and Joe's hinterland. I asked what made her want to write about these things.

"I'm not the sort of writer that can write ten pages about a man putting a sock on," she said. "I have actually got to have some sort of real drama in my books to develop my characters."

Mary was born and grew up in North Oxford. She used parts of her childhood in the book - Joe's school is based on St Barnabas School in Jericho, while Gordon is based on ex-colonials who she came across as a child in North Oxford.

"They were used to servants and kowtowing and they had no humanity at all," she said.

She came to writing late in life. "I only did it when I had the head space." That came when her two sons were at college, even though she was working full-time as a medical administrator.

"Once I took it up, I never ever let it go. I never thought I can't be bothered. I was always bothered."

She was inspired to write by Kate Atkinson's book Behind the Scenes at the Museum.

"I thought I don't have to write like everyone else, I can be unique, I can do wild things and I can get away with it."

She can, because she writes with great warmth and panache, making her characters believable and, apart from Gordon, likeable. She found writing male characters easy.

"I am a real man watcher. I've had male employers, before I was married I had boyfriends and I made a sport of watching them and realising that they're very different to women."

By contrast she finds it difficult writing women. "I don't know why. Maybe because I'm not very good at revealing myself."

The book was published earlier this year when Mary was 60.

"Mary Wesley started at my age or even older. She actually managed to sustain a career and that's what I want out of my writing, I want a career. I've still got a lot of energy and a lot of impetus."

She also has the nous to realise that to get books sold she has to generate publicity herself.

"I've been quite ruthless in being bold. I've never been like that before."

Boldness led to David Baddiel writing a bizarre column in The Times about how he was refusing to review the book as he'd only been sent it because he was a Jew. Great publicity for Mary and it resulted in a proper review in the paper. See what a bit of chutzpah can achieve.

The Crowded Bed is published by Transita at £7.99.