Diagnosed with stomach cancer, Harper Reed decides to end her marriage to Ethan Blake. Eight years earlier, at the graveside of Harper’s parents, Ethan had vowed to take care of her for the rest of his life; now, however, having lost his memory, he gravitates toward his former flame, Chloe Bennett—refusing even to believe in the history he once shared with Harper. Although Harper presents him with divorce papers, she still harbors a faint hope that, in the limited time she has left, he might remember her. Meanwhile, Chloe orchestrates a series of schemes—faking injuries and a pregnancy—that lead Ethan to repeatedly abandon Harper, leaving her alone in hospital rooms, at cemeteries, or outside a church.
Harper reserves a burial plot for herself beside her parents, only to watch in horror as Ethan destroys the headstone to appease Chloe. While Harper is praying in a church, a tragedy occurs; news of her death—and the vehicle transporting her remains—crosses Ethan’s path. Though he senses that Harper might be inside the vehicle, he chooses instead to head to his engagement ceremony with Chloe. It is only later, as Ethan begins to investigate his past promises and his own lost memories, that he finally realizes everything Harper had told him about her illness and their love was true. Harper, having survived, finds herself supported by Nathan Hayes, who remains by her side and gives her the courage to begin life anew.
As Ethan attempts to make amends, he discovers that Chloe’s web of lies extends far beyond a faked pregnancy. Following an explosion in a car accident—after which her fate remains briefly uncertain—Chloe returns, bearing scars. She kidnaps Nathan and Ethan, holding them in an abandoned factory that she sets ablaze, forcing Harper to make an impossible choice. Harper manages to rescue Nathan and escape, leaving Chloe trapped with Ethan; the police arrive just in time to pull Ethan to safety and arrest Chloe. An investigation at the clinic subsequently reveals that Chloe had bribed staff to swap embryo identification numbers—meaning the embryos originally frozen years ago had never actually been used.
With the truth finally exposed, Harper rejects Ethan’s plea to reconcile and marries Nathan in a church. Ethan leaves behind his assets, a letter of apology, and their original wedding ring, then walks alone toward the rooftop—the camera lingers on the ring box, blown open by the wind.