Louise Erdrich's 15th novel, "LaRose," entwines such weighty themes as war, family, adoption, death, grief, the Indian Child Welfare Act, reservation boarding schools, Indian culture and myth, and justice.

It's also a page-turner. And it's also, in parts, quite funny.

"Oh, good," Erdrich said, sounding relieved. "I was looking over my notebook a while back, and I had this giant note in the middle of my pages. And it said, 'PROBLEM. BIG PROBLEM. THERE IS NO HUMOR WHATSOEVER IN THIS MANUSCRIPT.'

"It's the hardest thing, writing humor into a book. But it's also essential. I just don't feel like I've got a book unless there's something funny in it."

Erdrich — slender, soft-spoken, dressed in black — was speaking in the backroom of Birchbark Books, the bookstore she owns in Minneapolis. It was late in the afternoon, and haunting pipe music wafted through the store. A woman browsed the shelves; a child laughed; in a secluded corner, a mother nursed a baby.

"LaRose," in bookstores on Tuesday, is not at its heart a funny book, but it is a very human book. It opens with tragedy, when Landreaux Iron accidentally kills Dusty, the 5-year-old son of his best friend and neighbor, Peter Ravich. Tragedy leads to further heartbreak when Landreaux and his wife give their own young son, LaRose, to Peter and his wife to raise.

That act, Erdrich said, comes from Indian tradition. "You read through traditional accounts, someone loses a child, whether anybody else is responsible or not, and someone else decides, 'Well, you raise my child.' Or someone is unable to bear a child, and someone else decides, 'Well, here, you help me raise my child. We'll do this together.' "

This fluidity of family is a powerful theme in "LaRose," with the Iron and Ravich families sharing not just the boy LaRose but also Ravich's daughter, Maggie, and the Irons raising not just their own children but also the son of another friend.

"This has always been a part of Native life, this ability to hand over a child to a sister, or to someone else, to raise for a while if you're having trouble," Erdrich said. "In my own family, my grandmother routinely adopted children for a period of time. They'd stay with her, or be raised by her, or go back to their own families after a time. And my mother, too — my parents also cared for other kids. That's always been the way I saw things."

This fluidity, she said, was misunderstood by Western social workers, who also took advantage of it, adopting Indian children out of the tribe, out of the community. Since the Indian Child Welfare Act of 1978, which makes it more difficult to remove children from their families, "the family system has been slowly building back up," Erdrich said. "So this is a book that has a sense in it of increased responsibility, increased resilience and strength."

An accidental trilogy

"LaRose" is the third volume of Erdrich's justice trilogy, following "The Plague of Doves" (a Pulitzer finalist), which explored revenge, and "The Round House" (winner of a National Book Award), which dealt with the theme of justice denied. She didn't initially see the three books as connected.

"I started thinking about each one long ago, but I didn't find them related internally until I was about halfway through 'The Round House,' " she said. "But one question led to another, and then I realized, ah, you know, I'm really writing something thematically linked."

Justice, she said, "is the foundation of a trusting society. It's the foundation of going forward and making a life. Justice is an enormous issue for this country."

Although the story of "LaRose" springs from darkness — the death of little Dusty, the ghosts of ancestors, the harshness of boarding schools, the ravages of chemical dependency, truly frightening Indian myths — this book feels lighter than some of her previous novels.

"What I think is warming about the book, or engaging about the book, are the relationships between people," Erdrich said, "and the fact that nobody ever really lets anybody else go, not really. I see that so often in families — the mending that occurs almost in a subterranean way and brings people back together even after something you think would sunder them forever."

The children in the book are a bright spot, providing much of the humor — such as when LaRose and Maggie steal a carton of Blue Bunny ice cream and eat the whole thing, burying the evidence in the barn (including the spoons); or when sisters Josette and Snow tease each other for using lofty language ("vocab words!") in their conversation.

Josette and Snow have big, generous hearts, and they sweep young Maggie, a damaged soul, into their lives naturally, doing her nails ("spa day!"), getting her on their volleyball team, gently warning her away from danger.

"The writing came alive for me whenever I got to them," Erdrich said. "I loved writing them, and I loved writing their relationship with Maggie. I think this is something about young women that isn't emphasized as often as the mean girl type of tearing down. But I also see this loyalty among young women, and a kind of friendship that is so fierce and protective."

Highly lauded, but shy

Erdrich, 61, is an enrolled member of the Turtle Mountain Tribe of Chippewa Indians. She was born in Little Falls, Minn., and grew up in Wahpeton, N.D., where her mother and father taught at a boarding school. She studied at Dartmouth College, a place she initially found lonely and a little overwhelming. In a 2010 interview with the Paris Review, Erdrich said, "At Dartmouth, I was awkward and suspicious. … I don't have a thick skin, and I especially didn't then. I obsessed over everything people said, ran it over forever in my mind."

She is still reserved, though supremely poised; she speaks carefully, pausing between thoughts. When talking about her daughters and sisters, she lightens, smiling broadly, but she grows serious again when discussing her work.

Erdrich has won a multitude of awards — a National Book Critics Circle Award, the Anisfield-Wolf Award, the National Book Award, a Guggenheim Fellowship, the Dayton Literary Peace Prize Richard C. Holbrooke Distinguished Achievement Award, the PEN/Saul Bellow Award for Achievement in American Fiction and others, including five Minnesota Book Awards.

Last year, Erdrich was awarded the Library of Congress Prize for American Fiction and so, after an appearance on Monday in St. Paul, her book tour will begin Tuesday in Washington, D.C., where she will read at a PEN/Faulkner event in collaboration with the Library of Congress.

From there it's off to New York, Chicago, San Francisco, Los Angeles. At this, Erdrich looks resigned. Book tours, she said, "combine two of my fears — air travel and public speaking."

The warmth of paper

Family is at the heart of the novel, and family is wrapped about the physical book, as well — dedicated to one daughter, Persia, and designed by another daughter, Aza, who has designed the covers of several of Erdrich's books. The author photograph is by Paul Emmel, Erdrich's stepson.

The script that says "LaRose" across the book jacket is Erdrich's grandfather's handwriting. "He was in several boarding schools," she said. "He was in Fort Totten, and he was in Wahpeton, and he also went to school in the Turtle Mountains. Every Native person has family members who went through boarding school," where they learned "gorgeous, beautiful, taut handwriting. Beautiful, symmetrical, spidery handwriting. I think that's very familiar to Native people, this script."

Erdrich writes her books by hand in unlined artist notebooks. "Sometimes I draw into the writing, or make a design," she said. "It's a visual and tactile way of working. I need that."

Sometimes she remembers to carry a notebook with her, but sometimes she forgets, and then she writes on whatever scraps she can scrounge up, which she later pastes into the notebook, collage-style: "I think part of 'Love Medicine' was written on Highway Host napkins," she said. "I wrote it at a booth in a Highway Host.

"I also have this whole story written on Black Bear Casino note pads. I started writing it and I went through the first note pad and then I got more from the housekeeper. This is great paper, it has a big bear on it."

Every 20 pages or so, "when I get a page buildup," she enters her words into a computer. "Then I get a printout — I don't read anything on a screen. I find it doesn't give me as much. I need the feeling of paper, the warmth of print on paper. So I have a printout, and I have a tiny little writing in between, basically a whole 'nother script within the script. The drafts become cleaner and cleaner as I work through them."

She's a saver, keeping notebooks, ideas, "scraps of writing" she leafs through sometimes in search of inspiration.

Some of "LaRose," she said, is "from 10 to 15 years ago and some of it is from three years ago and some of it is from a year ago. When I'm looking where my next book comes from, I sift through the notebooks. Put down ideas. Go back to them, and something clicks, something hooks me in. I look at my notes."

Some of the notes are useful, she said, and then, laughing, added, "And some of them are, 'THERE'S NO SENSE OF HUMOR WHATSOEVER. WHAT ARE YOU THINKING? THIS BOOK SUCKS.' "

Readers, of course, are almost certain to disagree.

Laurie Hertzel • 612-673-7302 • Twitter: @StribBooks • facebook.com/startribunebooks