Left on a train platform in an unfamiliar village, Saffron Faith Anders is certain her father will return shortly, like he promised. She holds out hope even as the hours pass and the station grows dark. When a strange old woman with a large umbrella approaches and inquires about her situation, Saffron doesn’t immediately trust the imposing do-gooder, but with the chances of her father returning growing ever slimmer, she agrees to rest at the old woman’s house. Her stay was supposed to be for a few minutes, but Saffron soon realizes she has been confined to a house of dark secrets.

Ever since Fern could remember, she and her mother have lived as servants in Wyndemere House, the old Gothic mansion of the Davenport family. She may have been a servant, but Fern developed a sweet friendship with Dr. Davenport's son, Ryder, and she was even allowed free range of the estate. But Dr. Davenport has remarried, and his new wife has very different ideas about a servant's place. Yet, for all her wrath, the cruel woman cannot break the mysterious bond between Ryder and Fern.

Caroline Bryer is the daughter of a very conservative TSA agent and former military brat, Morgan Bryer. Her mother, Linsey Bryer, is a descendent of the Sutherland real estate family. Their organized, suburban life in Colonie, New York is rigorously regulated and leaves little room for deviation from the norm. When Linsey, Morgan, and Caroline attend the wake of their neighbor Mr. Gleeson, they meet his charming daughter Natalie “Nattie” Gleeson, who works for the American ambassador to France. Linsey and Nattie strike up a fast friendship.

Sixteen-year-old Sage is a lonely child. Her adoptive parents watch her obsessively, as if studying her for warning signs of...something. And maybe they're right to - even she can't make sense of the strange things she sees and hears. She possesses knowledge that other teenagers don't, that her parents and teachers - no adult - could possibly have. So when Sage finally makes a friend who understands her alarming gift, he becomes her confidant, a precarious link to the truth about who she really is.

Alike in every single way...with one dark exception. As identical twins, their mother insists that everything about them be identical: their clothes, their toys, their friends...the number of letters in their names: Haylee Blossom Fitzgerald and Kaylee Blossom Fitzgerald. If one gets a hug, the other must, too. If one gets punished, the other must be, too.