In Walk Two Moons, the 13-year-old narrator, Sal, tells three interwoven stories. In the present, she’s on a cross-country road trip with her grandparents, Gram and Gramps, to visit her Momma, who’s “resting peacefully” in Lewiston, Idaho. While on the road trip, Sal tells her grandparents the story of her friend Phoebe Winterbottom, a lunatic, and Phoebe’s disappearing mother. And throughout both stories, Sal experiences flashbacks that tell the story of Momma leaving for Lewiston, about a year earlier.
Sal grows up on a farm in Bybanks, Kentucky, the only child of Dad and Momma. Momma loves trees, so when Sal was born, she named her Salamanca Tree Hiddle. Sal and Momma are very close; Sal is happy when Momma is happy and sad when Momma is sad. More than anything, Momma wants to have lots of children. Eventually, Momma she gets pregnant with her second child. But after Sal breaks her leg and Momma carries her home, Momma goes into labor early, and the baby is stillborn. Momma has to get a hysterectomy, and Sal blames herself for this turn of events.
Over the next few months, Momma becomes depressed. She cuts her long black hair short and gets on a bus headed west, insisting that she needs to figure out who she is. Momma sends Sal postcards from the various tourist attractions along the route. But two days before the last postcard arrives, Sal and Dad get the news that Momma isn’t coming back. Dad flies to Lewiston, Idaho by himself to see Momma. Sal stays home, and she’s upset when the singing tree—a tree that seems to emit birdsong all on its own—doesn’t sing.
A few months later, Dad decides to rent out the farm and move to Euclid, Ohio. In reaction, Sal throws tantrums, especially since she doesn’t have a chance to pack the treasures hidden under her bedroom floorboards: Momma’s hair and her postcards. Sal hates Euclid, where the houses are all small and close together. Sal especially hates the red-headed Margaret Cadaver, with whom Dad spends a lot of his time. Sal refuses to let Dad tell her how he met Margaret.
In Euclid, Sal meets Phoebe Winterbottom, who lives next door to Margaret. Phoebe has a wild imagination—she suspects Margaret is a witch and that Margaret probably killed Mr. Cadaver and buried him in her backyard. Sal finds all of this far-fetched. As she spends more time with the Winterbottoms, she’s intrigued by Mrs. Winterbottom, who seems to be the perfect housewife yet isn’t happy.
There’s a boy in Sal’s class named Ben, who seems to have a crush on her. He lives with his cousin, Mary Lou Finney, and it’s unclear where his mother is. He attempts to kiss Sal several times, and he makes a point to try to touch her—he notices that when another person tries to touch her, Sal flinches. Sal is annoyed at first, but she finds herself hoping that one of these times, she’ll actually be able to kiss Ben.
Things start to get strange when a young man, whom Phoebe insists must be a lunatic, comes to the Winterbottoms’ door asking for Mrs. Winterbottom. Around this time, Phoebe also starts finding envelopes with cryptic notes inside, such as “Don’t judge a man until you’ve walked two moons in his moccasins.” One day, Phoebe comes home to find her mother gone. Mrs. Winterbottom left three notes (one for Phoebe, one for Phoebe’s older sister Prudence, and one for Mr. Winterbottom) apologizing and explaining that she had to leave. Phoebe is convinced that the lunatic kidnapped her mother, and she pesters Mr. Winterbottom to go to the police, but Mr. Winterbottom thinks Phoebe is being silly.
Sal tries to support Phoebe through this trying time, but she finds Phoebe insufferable. She starts to see that Phoebe is leaning so hard on the story that Mrs. Winterbottom was kidnapped so that she doesn’t have to acknowledge that maybe, her mother just left. Sal starts to wonder if when Momma left, it wasn’t because of anything Sal did—maybe Momma was just unhappy.
Phoebe remains unconvinced, though, and becomes increasingly suspicious of Mrs. Cadaver. She becomes even more suspicious when she meets Mrs. Cadaver’s elderly and blind mother, Mrs. Partridge, and learns that her English teacher, Mr. Birkway, knows Mrs. Cadaver. When Mr. Birkway decides to read the students’ summer journals aloud to the class, he reads Sal’s story of Momma eating blackberries and kissing a tree, and Phoebe’s suspicions about Mrs. Cadaver. After reading Phoebe’s story, he comes to Phoebe’s house to share that he’s Mrs. Cadaver’s twin, and that Mr. Cadaver died in a car accident that also blinded Mrs. Partridge. He stops reading the journals after this.
Sal accompanies Phoebe to the police station on two occasions. They speak to a detective named Sergeant Bickle, who doesn’t take the girls seriously. But when Sal discovers that Sergeant Bickle’s son is the lunatic, she and Phoebe devise a plan and track down his son—Mike’s—address. One Saturday, they take a bus with Ben to a nearby city. Ben leaves the girls so he can go visit his mother, and the girls head to the college. There, they find Mrs. Winterbottom sitting on a bench, holding hands with Mike. When Mrs. Winterbottom kisses Mike on the cheek, Sal runs away. She eventually finds Ben at the hospital, who’s visiting his mother in the psychiatric ward. As Sal and Ben follow Ben’s mother around the hospital grounds, they kiss.
The next day, Mrs. Winterbottom returns home with Mike and introduces him as her son. She gave him up for adoption years ago, and she’s never told Mr. Winterbottom about it. Incensed, Phoebe leaves the house with Sal and discovers that Mrs. Partridge has been leaving the notes on her doorstep. Sal suddenly decides to go speak to Margaret and discovers why Dad is so interested in her: she knew Momma.
Now, in the present, Sal is getting ready to goes on the road trip with her grandparents to see Momma. She hopes she can bring Momma home if they get to Lewiston by Momma’s birthday, which gives them seven days to make the trip. Gramps makes lots of stops along the way, at all the places where Momma stopped while she was on her trip. They wade into Lake Michigan, dance with Native Americans in Wisconsin, and skinny dip in the Missouri River. This results in Gram getting bitten by a water moccasin and spending a night in the hospital. She’s weak after this, but still enjoys the trip—and she especially enjoys seeing Old Faithful in Yellowstone. As they travel, Sal tells them the story of Phoebe and Mrs. Winterbottom.
When Sal, Gramps, and Gram get to Coeur D’Alene, Idaho, Gram has a stroke and is hospitalized again. It’s late at night, and Momma’s birthday is the next day. Gramps gives Sal the keys in case she needs anything from the truck, but he and Sal both know what Sal is going to do. Very carefully, Sal gets in the truck and drives the last 300 miles to Lewiston. Halfway down the steep, winding road heading down to the town, she stops at a lookout point. From there, she gets out and walks into the brush, out to where there’s a bus turned over on its side. This is where Momma died.
The Lewiston sheriff is waiting at the truck when Sal gets back from the bus. When she realizes who Sal is, he drives her to Momma’s grave, where Sal says goodbye—she fully believes now that Momma is dead and isn’t coming back. Then, he and a deputy drive Sal and the truck back to the hospital in Coeur D’Alene, where they learn that Gram died in the night. Sal also tells the sheriff why Dad is so interested in Margaret Cadaver: Margaret was the only person to survive the bus accident that killed Momma. She sat next to Momma on the bus, and Momma told her everything about Sal and Dad. Dad met Margaret in Lewiston when he flew out to bury Momma.
Not long after the road trip, Dad and Sal move back to the farm in Bybanks. Sal is looking forward to an upcoming visit from many of her friends from Euclid, including Margaret, Ben, Phoebe, and Mr. Birkway. She hopes that she and Ben will be able to kiss some more.
