It all starts with a mysterious phone call from Louisa's decorative antique phone. And that wouldn't be so strange, except that the phone is unplugged, and has been for years. Frightened by the call and its message—and questioning her own sanity—Louisa listens as a somehow-familiar voice describes a lost family secret about Louisa's grandfather and his daring involvement in resisting the Nazi scourge in his native Sweden during World War II. Piecing together each clue she can find, Louisa begins to see how her grandfather's guilt and shame continues to haunt her own father, and the rest of her family, decades later, planting seeds of doubt that threaten to tear them all apart.
Now desperate to know the full truth, despite the charming distractions of a boy with secrets of his own, Louisa becomes consumed with her discoveries, which she passes off to her parents as a school history project. Digging through old family albums and letters, she at last begins to see that the phone call was only the beginning, and that she is the one meant to be the messenger who can bring the truth of the past to light—before it's too late for her family.