What an unexpected book "The Blue Notebook" is -- a first novel by James Levine, a Mayo Clinic physician and Oronoco, Minn., resident who tells the disturbing story of a teenage sex slave living, if you can call it that, in the slums of Mumbai.

And what an unexpectedly fine book it is.

Fifteen-year-old Batuk, who has been sold into prostitution by her Judas of a father, does her ugly forced labor in a stinking "nest" with barred windows on Mumbai's Street of Cages, guarded by a foul matron who runs this loathsome enterprise for a rich businessman. Given the betrayals and abuse that Batuk endures, she should be beaten down -- no, she should be dead -- but instead she is plucky and stubborn, a born survivor who finds glimmers of joy in friendships with her fellow sex slaves and in writing about her days and dreams in a secret notebook. (She learned to read and write while in a tuberculosis hospital, we learn in one of the novel's frequent flashbacks.)

Batuk's narrative is graphic and heartbreaking. The euphemisms that pock her journal -- "making sweet cake," for instance, is sexual intercourse -- remind us that she is a mere child trying to make sense of the horror that is her daily life.

This book is not for the faint of heart. In one of its many wrenching moments, a harsh old hag badgers Batuk in preparation for the girl's first sex client (who has paid extra for the sick privilege of deflowering a child), holds her down during the rape, then wordlessly weeps as the teen lies shocked and bleeding, initiated into her awful new life. Although the book does not say so, we suspect that the old woman, too, was once treated this way.

Levine has said that he was inspired to write the book while visiting the Street of Cages with a U.N. contingent. There he saw a girl in a pink sari scribbling in a notebook as she awaited customers.

"The Blue Notebook" is not merely a high-minded indictment of injustice. (Its publication, however, will do good in the world; its U.S. royalties are going to the International Center for Missing and Exploited Children.) It is a work of art, and a finely rendered one.

The book's twisted mix of despair and hope reminds one of Charles Dickens one moment, Elie Wiesel the next. How a privileged American physician managed to channel the spirit of a street urchin is nothing short of astounding.

Perhaps this will be the only novel Levine will ever write, but it's a small masterpiece. It will change the way you think about humanity and your place in it. How many books can claim that?

Pamela Miller is a Star Tribune night metro editor.