Young, independent and sharply aware of her spiritual weaknesses, Sister Agnes Bourdillon is not the kind of nun who needs a habit and a wimple to express her religious commitment. Approaching her final vows in the order, after six years as a novice, Agnes is dreading leaving the solitude of her Bermondsey flat to join the rest of the community in Hackney. If she takes the vow of poverty, she will have to give up a house she owns in Provence, bequeathed to her by her mother. Her mentor, Father Julius, tries to allay her fears, yet Agnes is not comforted. A temporary respite from the decision is her work in an addiction center near her home.

One of the residents, Walker Hogan, a dried-out alcoholic, is stabbed in a street brawl and dies in hospital. Before his death, he had confided in Agnes, and given her pages of his writing--a war diary--to read. At his funeral, she is surprised to see that the coffin is plush and obviously expensive, but thinks no more of it until a man turns up at the hostel looking for information on Walker. His story is intriguing, and Agnes decides to investigate. This decision will cost her dearly, and take her on a journey that will challenge her beliefs and her physical safety.