From childhood, Katherine knows she is different, and that her parents are not who they seem to be. But in becoming a mathematician, she must face the most human of problems-who is she? What is the cost of love, and what is the cost of ambition? On her quest to conquer the Riemann Hypothesis, the greatest unsolved mathematical problem of her time, she turns to a theorem with a mysterious history that holds both the lock and key to her identity, and...

Before everything changed, young Hannah Rosenthal lived a charmed life. But now, in 1939, the streets of Berlin are draped with red, white, and black flags; her family's fine possessions are hauled away; and they are no longer welcome in the places that once felt like home. Hannah and her best friend, Leo Martin, make a pact: whatever the future has in store for them, they'll meet it together. Hope appears in the form of the SS St. Louis , a transatlantic...