It's 1967 and twelve-year-old Bea is in need of some adventure. Her mother is off in San Francisco, while her father has just gotten remarried in Los Angeles. Bea has gained a younger stepsister, and she's not thrilled about her blended family. So when her ailing grandmother, Pidge, moves to an Orange County senior-living community and asks if Bea would spend the summer helping her get settled, Bea is happy for any excuse to get away.

But it turns out, her grandmother isn't interested in settling in. What she really wants is to hop a train back to Atchison, Kansas--where she thinks she'll be reunited with her long-missing sister: Amelia Earhart. And she wants Bea to be her sidekick on this secret trip.

At first, Bea thinks her grandmother's plan is a little crazy. But Pidge has thirty years of letters written in "Meelie's" unmistakable voice, all promising to reunite. This might be the adventure Bea needs...

With letters in hand, Bea and Pidge set off on their quest to find Amelia. But getting halfway across the country proves to be more of an adventure than either of them bargained for. And their search for Amelia leads to some surprising truths about their family--and each other.