It seems perverse to call a book as dark as this one "light." But there is a certain denseness, a cultural and psychological richness, in most of Louise Erdrich's work that's largely missing from "Shadow Tag." Though the Native American background and Midwestern setting remain, Erdrich's focus here narrows on a couple and, to a lesser extent, their three children. These children -- 6, 11 and 13 -- are somehow at once peripheral to the story and its catalysts, critically disturbing the already uneasy balance between their passionate and deeply troubled parents. The book begins with Irene America's Blue Notebook, an alternate diary she has begun -- and keeps in a safe deposit box -- after discovering that her husband, Gil, has been reading her real, long-term journal, the Red Diary. This betrayal, the reading of the diary, is apparently the breaking point for Irene, though when it becomes clear that Gil has been abusing both her and the children, it's hard not to wonder why this particular invasion of privacy is the worse offense.

Gil is an artist -- explicitly a Native American artist -- who has made a career of painting Irene; and Irene is a "brilliant" scholar who put her research into George Catlin, 19th-century painter of Native Americans, on hold for her family and is only now trying to return to her work.

Going back and forth between the Blue Notebook (the genuine one) and the Red Diary (now used to manipulate and mislead Gil) and the points of view of Irene, Gil and the children, Erdrich offers a portrait that's convincing to the point of squeamishness of a family sprung from two people with outsize personalities who need and despise each other in equal measures.

The book's guiding metaphor is shadow tag, a Native game in which the object is to step on an opponent's shadow. "He had stepped on her shadow," Irene thinks of Gil, considering the role of her image in his art. And shadows come into Erdrich's discussion of Catlin's art, which Irene shares with her daughter, and in the rare, innocent moments of the family's play -- which shed their innocence when Gil, through his position, manages to be the only one without a shadow.

What's unfair, I suppose, is the shadow that Erdrich's own work throws over this novel. This is no "Love Medicine" or "The Plague of Doves." And yet, even if it is a different sort of novel for this author, it is wonderfully, painfully readable and revealing in its own way, owing more to raw emotion than to deliberation.

Ellen Akins is a novelist in Cornucopia, Wis.