When Sharon Dogar was writing her novel Waves, she spent a lot of time wondering whether people would want to read it - she thought it was such a weird story. It features 16-year-old Charley, lying in a coma in Oxford, and her 15-year-old brother Hal, on holiday in Cornwall, who begins to hear her communicating with him, urging him to discover the truth about the accident that sent her into a vegetative state.

While 'weird' may be one word for it, 'supernatural' another, neither do justice to Sharon's talent as a writer. One can easily see how Waves was picked off the slush pile at the literary agency PFD, and eventually endorsed by her former teacher, Philip Pullman.

The story sucks you into its undertow and beaches you, gasping, 345 pages later, wondering how she wrote such an enthralling, insightful, ultimately uplifting book about a girl who may or may not be dying.

Narrated in turn by Charley and Hal, the action switches between the year before to the present day (described in the book as then and now). The year before, Hal had found Charley's almost lifeless body in the sea. Now he is back at the beach, on holiday with his parents and younger sister Sara. The story which gradually unfolds through the prism of Hal's investigations and Charley's increasing infiltration of his mind is a tale of first love, jealousy and surfing. It is also a powerful study of how grief is often held in angry limbo when one member is in a persistent vegetative state.

It is published by Chicken House, an imprint run by Barry Cunningham, who discovered J. K. Rowling. The journey to publication has been a long one for 44-year-old Sharon, who has wanted to be a writer since she was four. "I can remember that sense of being held by words and by books," she said. "It's such a safe place to be, in the world of a book. When you're growing up, there's such security, as well as learning and excitement, and you can write about difficult things."

She got lots of encouragement from three teachers at her middle school in Blackbird Leys, who, remarkably, all went on to publishing success - the poet John Foster; Rod Hunt of the Oxford Reading Tree books; and Philip Pullman.

"Rod and Philip were both very enthusiastic about my writing," she said. "They were very flexible and very good at thinking: 'You're good at this, you've learnt how to do commas, why make you do it for another hour? Go and read a book. Go and finish that story'."

After school, Sharon partied hard for three years at London University while studying English literature and comparative religion, travelled round Pakistan on her own and then came back to Oxford, where she has lived since, marrying and raising three children.

She was a hearing therapist for many years, then trained as a counsellor, taking an MA in psychoanalytic studies. She now works with young people. Waves was written before she began doing this, however, and she is keen to point out that none of her clients, even unconsciously, could be in the book.

During the intervening years, she wrote novels, short stories and poetry for fun, but never seriously tried to get published. She got in touch with Philip Pullman after reading one of his early books and has maintained contact ever since. "Because I'm a bit naïve, I didn't realise that because of the connection with Philip, people would just assume that's how I got published," she said.

If anyone helped her, it was his wife Jude, who told her to start sending books to agents. "She said: I bet you can write.' So I said: How do you know?' And she said: I just know.'" Much later, Sharon asked her if she really had known and Jude admitted she hadn't, she was just being bossy. However, It gave Sharon the spur she needed. "I thought: 'She's so right. I've got to actually do it, take it seriously'. So I did and here I am."

When we met, Sharon was still obviously very excited about finally getting a book published. Earlier in the day, she had been into Waterstones in Oxford and found a poster for it on display. While she was standing there, staring, a shop assistant came up and asked if she was the author. Sharon asked her how she could tell. "You all get a look when you're looking at your own books," was the reply. Sharon thinks it was probably a look of disbelief.

She said: "I keep thinking about that Julie Andrews song, I Must Have Done Something Good. I wish I knew what it was, so I could keep on doing it." Presumably, the years she spent honing her craft were at least partly responsible; the ambitious structure and fractured narrative are the hallmarks of a seasoned writer. The story comes from the heart, which is why it's so powerful. Not weird, just wonderful.

Waves is published by Chicken House at £10.99.