To unruly-red-haired sixth-grader Kit Higglby, her last name carries the shameful stamp of cowardice and crazy going back generations-one that makes her a target of bullies at school. Then Kit discovers her family tree...the actual tree! It takes her on a time-travel adventure to America's Old West and toward her roots which embrace Irish, Viking, and Lakota traditions, all forcing her to confront her "whiteness," the importance of honoring one's ancestry, and the value of true friendship.

Wherever Kit goes, her family's background causes her trouble. Dubbed 'Kit Kat the junkyard rat' at her private school due to her divorced dad's job as a junk collector, the Higglby name only further serves to make life difficult for the middle-schooler. Her great-grandfather spun crazy tales about the "Forbidden Forest" near the family farm. But now Kit at least lives across town with Grace, a beloved horse owned by her mom and megarich stepdad, and she is has her horse-club friends-that is, until she doesn't. Kit wants to rebrand herself, but for now takes comfort in maybe making a new friend Whitney...a Black student at the public school.

During a horrifying visit to the Forbidden Forest, Kit meets a boy a teenage boy who claims to reside inside a tree. Bringing Whitney along, Kit finds a fantastical parallel universe within this very special tree, one where all of the Higglby family members who have ever lived come to dwell after they die, protected by the construct of the tree...Vikings, French, Native Americans, and more.

On a mission involving her Lakota great-grandmother many generations removed, Kit and friends undertake a trip to the 1800s along the Oregon Trail to return a pouch of sacred objects Sespasa swore to protect for her Lakota people. On the journey, Kit meets people capable of terrible acts of cruelty to Lakotas, freed slaves, and each other. Along the way, Whitney helps expand Kit's once-sheltered perspective, and a condescending white worldview that can bring hate and harm to others.