Susan Sontag (1933-2004), Sigrid Nunez admits, is an acquired taste. She did not write beautiful sentences, and she failed to create the great novels that she thought it was in her to produce. And yet on certain subjects -- such as photography and cancer -- she is quotable and debatable. A controversial writer, she loved to start arguments. She got into trouble with leftists when she called communism "fascism with a human face" and offended photographers when she doubted photography was an art.

Nunez, unfortunately, does little to coordinate the person with her prose. Nothing wrong with dwelling on the intimate details of Sontag's life -- she is a fascinating subject -- but to what end? Nunez claims that she does not understand why Sontag got such a reputation as a humorless person, and then spends pages showing just how humorless Sontag could be. So she laughed at other people's jokes -- that hardly seems like much of a revisionist interpretation.

Nunez really gets going, though, near the end of the book when she probes Sontag's trouble: For all her fame, Sontag saw herself as a failure. Hence her rages as she projected her frustration on others. Nunez does not claim to explain Sontag, but she does offer insights on how it all went terribly wrong for a writer who began with such promise.