In "The Twelve Tribes of Hattie," first-time author Ayana Mathis walks upon some of the richest thematic terrain our country's history can offer a novelist.

Her protagonist, Hattie Shepherd, arrives in Philadelphia from Georgia in the mid-1920s, one of a legion of travelers in the great migration, that movement of African-Americans from the Jim Crow South to the relative freedom of the North.

This month the recently relaunched "Oprah's Book Club 2.0" chose "Hattie" as its second selection. Thousands of people will soon buy a copy of it, but those who read expecting a great work of narrative art are going to be disappointed. "The Twelve Tribes of Hattie" is a competently written melodrama that only intermittently achieves anything resembling literary excellence.

Mathis is a graduate of the famous Iowa Writers' Workshop, and her work is not lacking in ambition. It begins in 1925, with teenage Hattie's arrival in Philadelphia. An illness has beset her two infant children. They have names that sound beautiful and hopeful to her Southern ear: Philadelphia and Jubilee.

With a series of interlinked short stories, Mathis brings the narrative of Hattie's progeny all the way up to the 1980s. We see her children grow up, and Hattie herself suffer into an embittered middle age.

The novel's scope is epic, but its ambitions sink in a sea of flat prose, including many waves of simple, declarative sentences. Mathis often gives us scenes that are devoid of all but the most generic physical details, with uninspired dialogue and cliched similes as filler.

Consider the passage in which Hattie's sister Pearl arrives with her husband Benny to adopt one of Hattie's children. By then, Hattie has so many mouths to feed, she's on the dole to make ends meet. It's one of the most dramatic moments in the novel, but Mathis doesn't have quite the linguistic gifts to make the scene come to life.

Hattie's resentment toward her better-off sister produces a series of predictable observations rendered in a monotone of short sentences: "Benny opened Pearl's door. He had always had good manners. Pearl was powdering her nose like a princess. She looked well-fed, manicured."

Not all of the writing in "The Twelve Tribes of Hattie" is that pedestrian. The novel begins with a vivid and tender description of the deaths of Hattie's two babies as she scrambles across Philadelphia in a search for eucalyptus leaves and other country remedies to save them.

That scene is gut-wrenching because Mathis is able to portray Hattie as a disoriented innocent in the big city. But Mathis seems incapable of imagining her characters as anything but confused, distraught or overwhelmed. Nor is she much interested in the physical, sensory world they inhabit.

One imagines that Philadelphia was a city vividly transformed by the great migration. But you won't see Philadelphia come to life in "Hattie." Mathis only provides a few street and neighborhood names to suggest the originality of the city where much of her story unfolds. The spirit of reinvention, possibility and cultural tumult that defined those years is largely absent too.

Mathis is more successful in her descriptions of the inner turmoil of two of Hattie's sons: one a musician confused about his sexuality, the other a teenage preacher who's heard the voice of God.

Hattie's own emotional struggles as a mother of eight are given the stark, superficial treatment of your average afternoon talk show. Poor Hattie is pummeled again and again by fate and injustice. Her life as a character in this book is defined almost entirely by the fact that she bears children.

Nothing, it seems, is able to liberate the characters in "The Twelve Tribes of Hattie" from the melodramatic prison in which Mathis has placed them.

As the year 1968 arrives, we find Hattie's affluent, now-adult daughter caught in a kind of Victorian-era drawing-room drama with the hired help, without a hint of the seismic shifts in attitudes that are sweeping through the country.

Even the sex scenes in "The Twelve Tribes of Hattie" fall victim to Mathis' matter-of-fact writing voice and its use of verbs - "emboldened," "resolved" - more appropriate to a politician's stump speech.

In the end, "The Twelve Tribes of Hattie" is a callow work by a writer of still unpolished talents. Our great novelists give us fully rounded characters whose lives reflect the limitations, the possibilities and the wonder of the times in which they live. Mathis gives us a one-dimensional portrait of their suffering and little else.