Grace and Hope are identical twin sisters born with the ability to time-cross together between 1692 Salem, Massachusetts, and 1912 New York City. As their twenty-fifth birthday approaches, they will have to choose one life to keep and one to leave behind forever—no matter the cost.

In 1692, they live and work in their father's tavern, where they must watch helplessly as the witch trials unfold in their village, threatening everyone. With the help of a handsome childhood friend, they search for the truth behind their mother's mysterious death, risking everything to expose a secret that could save their lives—or be their undoing.

In 1912, Hope dreams of becoming one of the first female pilots in America, and Grace works as an investigative journalist, uncovering corruption and injustice. After their parents' orphanage is threatened by an adversary, they enter a contest to complete a perilous cross-country flight under the guidance of a daring French aviator.

The sisters have already decided which timeline they will choose, but an unthinkable tragedy complicates the future they planned for themselves. As their birthday looms, how will they determine the lives—and loves—that are best for both of them?