Isabel Griffin has done her best to move on since her boyfriend, Max Adair, vanished without a trace eight years ago, leaving her heartbroken-and pregnant. Eerily enough, this isn’t the first time someone Isabel loves has gone missing. When she was sixteen, her mother disappeared, and her father became obsessed with finding his long-lost wife-at the expense of parenting Isabel.

Determined not to repeat her father’s mistakes, Isabel works hard to become a respected archaeologist and a loving mother to her daughter, Finn, a little girl with very unusual abilities. But while Isabel is on a dig in Barbados, she receives a disturbing phone call. The hauntingly familiar voice on the other end speaks just four words-“Isabel. Keep her safe.”-before they’re disconnected.

Isabel tries to convince herself that the caller can’t possibly be Max. But what if it is, and Finn is in danger? As one mysterious event after another occurs, she can’t shake the feeling that, despite what everyone else believes, Finn’s father is alive-and he’s desperately trying to reach her.

Before Madeleine Kimble’s mountaineer husband, Aidan, climbs Mount McKinley’s south face, he makes her a solemn vow: I will come back to you. But late one night, Maddie gets the devastating news that Aidan has died in an avalanche, leaving her to care for their son-a small boy with a very big secret. The call comes from J. C., Aidan’s best friend and fellow climber, whose grief is seasoned with survivor’s guilt . . . and something more. J. C. has loved Maddie for years, but he never wanted his chance with her to come at so terrible a cost.

Across the country, Nicholas Sullivan wakes from a motorcycle crash with his memory wiped clean. Yet his dreams are haunted by visions of a mysterious woman and a young boy, neither of whom he has ever met. Convinced that these strangers hold the answers he seeks, Nicholas leaves everything behind to find them. What he discovers will require a leap of faith that will change all of their lives forever.