Anne Enright won the Man Booker Prize for her last novel, "The Gathering," which was an edgy ensemble drama about a large Irish family in mourning. At first glance, her new book seems a more limited affair, if you'll forgive the pun, for it is a novel about an adulterous relationship.

However, Enright is too canny a writer to write about a subject like adultery and leave it at that. Her method is not dissimilar to that used by Richard Ford in another notable book about cheating, the short story collection "A Multitude of Sins." Here too the word "adultery" covers a multitude of sins -- with the added twist that it is set in a society, contemporary Ireland, in which the receding tide of religious influence has left people without the old certainties. As narrator Gina Moynihan slyly points out about her niece's education, the term "failure to love" is now favored in school over that heavy word "sin."

So what are we to make of Gina, and what is she to make of herself? This young IT professional is a creature of Ireland's "Celtic Tiger" boom, and aware of being so. She has bought into the "Sunday-supplement" materialism of the good times, but is also capable of getting a pinch of ironic distance from that self-congratulatory culture. Hence the dead-on description of her fashionable workplace, Rathlin Communications:

"It's the kind of place where the lift is big enough to bring your bike upstairs, and the coffee is all fair trade."

She's something of a problem case, Gina, especially to herself. Hers are sins of both omission and commission. She has failed to love, and succeeded in loving. Just as the Celtic Tiger begins to die on its feet -- bubbles, and not just the big one related to property, are bursting all over the place -- she has an affair with an older, married man, Sean Vallely, eventually leaving her own husband, the stolid Conor, to set up house with Sean.

This involves him leaving the picture-postcard village of Enniskerry, where he lived with his brittle wife, Aileen, and young daughter Evie, who suffers from a form of epilepsy. As things settle down, or as much as they can in a time of both economic and psychological turmoil, Gina develops a relationship of her own with Evie, and begins to assess the consequences of what she has done, and what she has failed to do.

"The Forgotten Waltz" is a subtle and suggestive novel. Its Achilles heel is that the chemistry between Gina and Sean is not quite convincing or apparent enough -- he remains something of a stuffed shirt. But confessions from Gina such as "I had gone to the edges of myself, and what was in the centre was anyone's guess" resonate in all sorts of interesting ways.

Robert Cremins teaches in the Honors College at the University of Houston and is the author of "A Sort of Homecoming."