Nature sets the mood in A Crooked Tree. Mannion paints vivid and emotional word pictures of Valley Forge Mountain, Pennsylvania, which has an adolescent hold over first-person narrator Libby Gallagher. Like the mountains she so loves, Libby symbolizes America's revolutionary spirit and sense of itself. It is the late 1970s. Libby's mother is driving the family home - Libby, Ellen, Marie, Thomas, and little Beatrice. Just as they get to the Pennsylvania Turnpike - "the road to nowhere" - Ellen starts giving their mother attitude about Bill, her overweight boyfriend. Kicked out of the car, Ellen is forced to walk home alone.
Libby is afraid of the days ahead, with 18-year-old Marie leaving home, independent Thomas, a dead father and a mother with a boyfriend. Appalled that her mother kicked Ellen out of the car, Libby wants to find her sister, who she's certain is still walking home. When Ellen turns up at Mrs. Boucher's place while Libby is babysitting with a strange and terrifying story, the arrival jumpstarts the search for a spooky man in a Camaro with white hair like a Barbie.
How far did Ellen actually walk? A local boy, Wilson McVay, starts organizing people to find the perpetrator. Mrs. Boucher says "Your mother needs to know, Libby. Ellen should see a doctor." Libby knows Wilson is going to take the law into his own hands. Adding to her stress is her mother's distracted air and the grief Libby still feels for her father, who is a serious presence throughout the novel.
Libby finds solace walking in the woods and on the paths on the top of High Point Lane. The splinters of moonlight, like markers in a fairy tale, tell Libby that she's on the path toward "the crooked tree." Her dad called the tree "a way-finder" and told her that Indians bent the tree when it was a sapling and made it grow that way. Tonight, a wave of panic washes through Libby. Will Wilson carry through with his threat? Mom can't find out; she'd kill Ellen for hitchhiking, so they've all agreed not to breathe a word - especially Sage, who is the same age as Thomas, and Jack Griffith, a boy in Libby's class who Libby quite likes.
Mannion captures the mountain life of the 1970s. Everyone either listens to rock or heavy metal, and girls like Marie wear black vintage clothes, fishnets and Doc Martens. The music you like and what you wear say a lot about who you are and who you hang out with. Libby is angry that Marie is leaving, "angrier than I could ever remember." She hates her mother and Jack, but she mostly hates Marie for moving to the city and leaving her alone with all the worry of Wilson, Barbie Man and Ellen.
Only in the woods by the crooked tree does everything diminish to the hum of the ground and the light rustle of leaves. In high summer, everything feels lush and alive. Libby understands the feeling of death, "how sadness could be in your body even when it wasn't in your head." Libby always seems to see beyond the spectacle of her own disillusionment. Along with her painful self-consciousness, Libby is very self-aware.
Set against the 4th of July parade, the thrilling climax features the return of Barbie Man. Everything moves in slow motion for Libby as the drivers slow down to gape while Libby frantically searches for Ellen's pale face. Though she doesn't know it, this will be Libby's last summer on the mountain. She wants to go back "to before," to hold her family together in the car as they drive through Pennsylvania, "squished and inseparable."
Mannion delicately unfolds "that summer" when a desperate Libby tries to reel in those she loves. Mannion makes us empathize with Libby - her sense of alienation and loneliness, her longing for her father and her frustration at the world around her. Perhaps the loneliness that young people like Libby feel is part of the human condition, not just a phase.