Escaping from her harsh school before finding work as a maid in an English boarding house, Louisa realizes that her mysterious employer and his staff execute cruel judgments on the guests.

After twelve-year-old Lark, determined to escape her squalid life, steals a magical sword from the Royal Museum, she reluctantly becomes the next Nightingale, destined to vanquish an ancient evil.

When her grandmother decides to ditch assisted living and start a boarding house, fourteen-year-old Amanda Jane Keeling, or Rebel, signs on for the work crew, where she just happens to meet a teenaged boy taller than she is and to embroil them both in a mystery.

In 1934, during the Depression, Kit's cantankerous uncle comes to live in the Cincinnati boardinghouse run by her parents, enlisting her aid in transcribing his complaining letters to the editor of the local newspaper and inspiring her to write a different kind of letter of her own.