Maya and Rebecca Ward are both accomplished physicians, but that's where the sisters' similarities end. As teenagers, they witnessed their parents' murder, an event that left Maya cautious and timid, while Rebecca became the risk taker.
After a devastating hurricane hits the coast of North Carolina, Rebecca and Maya's husband Adam urge her to join them in the relief effort. But when Maya's helicopter crashes into raging floodwaters, there appear to be no survivors.
Forced to accept Maya is gone, Rebecca and Adam turn to one another, unaware that, miles from civilisation, Maya is injured and trapped with strangers she's not certain she can trust. Now, away from the sister she's always relied upon, Maya must find the courage to save herself — unaware that the life she knew has changed forever.