These days it's fairly common to have parents of different religious denominations. While no one could argue that it makes life any simpler, it is not unusual to identify with two faiths. But what about three? Sadia Shepard grew up in Boston, raised by a white Protestant father, Pakistani Muslim mother, and her beloved maternal grandmother Nana who, when Shepard was 13, revealed that she was originally from the tiny Bene Israel community in India.

Nana had followed the man she loved to Pakistan during partition and, as she promised him, raised their children, including Sadia's mother, as Muslims. But in her old age, Nana seems to be drawn back to Judaism.

The Bene Israel are considered one of the Lost Tribes, shipwrecked on the Konkan coast of India 2,000 years ago. Isolated from other Jews, they retained an idiosyncratic but faithfully practised collection of rituals, but most have made aliyah, leaving a shrinking, elderly community.

After her grandmother's death, Shepard was determined to discover more about the remaining community and set off for India with a camera and a mimeograph of her grandmother's family tree, spending more than a year capturing the Bene Israel. In doing so, she came closer to understanding her own rich and complicated heritage.

The resulting book, Footpaths in the Painted City: An Indian Journey (Atlantic £12.99), is full of wonderful material - from the detail of a Jewish pre-wedding ceremony involving beaten rice and coconut, five types of fruit, and unrefined "jaggery" sugar, to the community's devotion to the unimaginably distant Israel. Shepard captures it all with her keen, film-maker's eye. She also writes with an engaging honesty about her own journey, her love for her grandmother, and the conflicting forces in her own identity.

She combines the deeply personal with the sweeping story of a people. It reads like a beautiful, enthralling novel, depicting and honouring a Jewish community quite unlike any other.