New York Times bestselling author Margaret Peterson Haddix, the master of cliffhangers, delivers a pulse-pounding mystery perfect for fans of Jacqueline West and Kat Yeh, full of secrets, surprises, and the power of family.

One minute they're there: laughing and having fun at the house next door. The next minute, the teens are gone. Like magic. Marin can't believe her eyes. Who are they? Can anyone else see them? What makes them so happy?

Marin is lonely in this new town of hers and eager to figure out more. Then she meets Charley, who reveals that he knows about them, too.

He calls them the "Remarkables." Charley warns her to stay away from the Remarkables—and him. Charley and Marin both have painful secrets they're holding on to, but could solving the mystery of the Remarkables help them both?

In addition to building an intriguing world filled with mystery, Haddix also grounds the story with real issues that many children face. Characters deal with the complexities of bullying, the guilt children experience when parents have addiction issues, and the uplifting power found in strong families of all shapes and sizes.