Set in 1849 Missouri (at least at first), the book follows protagonist Samantha and her friend Annamae. When they kill a man in self-defense, they disguise themselves as boys, take the names Sam and Andy, and set off on the Oregon Trail. They meet up with three cowboys and become True Companions as they head west.
This book provides examples of:
- A Cappella: The cowboys occasionally sing something silly like Yankee Doodle. Andy sings hymns this way.
- Attempted Rape: Yorkshire tries to rape Samantha. She kills him.
- Berserk Button: Andy and onions. She doesn't even want to see them and throws up when she's unknowingly fed soup with onions. (Peety, who cooked the soup, didn't know.) The first time this comes up, Sam sees that it's a serious feeling and treats it as such; she's right.
- Bittersweet Ending: Andy meets up with her brother, Isaac, but he dies shortly after; and after many injuries and near-death experiences they still have a long, dangerous road ahead.
- Black Dude Dies First: Averted. The death of Sam's dad, who is Chinese, kicks off the plot, but the main characters are a diverse group.
- Chekhov's Skill: The sweetheart knot is used twice to save a protagonist's life. Sam's musical skill is also key.
- Death of a Child: There's the baby the Broken Hand Gang killed, as well as Jeremiah.
- Eastern Zodiac: Sam believes in it and references it frequently.
- Everybody Knew Already: The girls' disguises. Peety claims he saw through them on the first day, when Andy tried to button her coat the wrong way.
- Funetik Aksent: The Scotsmen have their accents spelt out phonetically.
- Insurance Fraud: Sam realizes this has been committed by Yorkshire, who intentionally burned down the Whistle.
- Interrupted Suicide: Sam tries to drown herself after her father dies; Andy interrupts.
- Intimate Healing: When West has a fever after being kicked by a horse, he won't drink from a spoon, so Sam feeds him soup from her mouth.
- MacGuffin: Sam's mother's bracelet. While it was given away for a reason, any other valuable object could be substituted in.
- Nobody Poops: Averted. Sam and Andy take bathroom breaks together to keep watch for each other and maintain their disguises, claiming that relieving yourself in public insults Chinese and African ancestors. They also use this time to speak to each other honestly, which leads to Peety remarking that it takes Chinese and African people a long time to build their log cabins.
- Short Cuts Make Long Delays: The shortcut that turns out to be a dead end.
- Street Musician: Sam and her father both played instruments; she mentions earning money for rent this way.
- Token Minority: Averted with the main characters Sam (Chinese) and Andy (African-American), as well as secondary character Peety (Latino).