Ji-won, suffering from cancer, discovers her friend Su-min's affair with her husband. Overhearing them plotting to profit from her death, she is murdered but wakes up in 2013.

Ji-won goes back 10 years and discovers that fate governs events. He tries to give her fate to Su-min by trying to match her with her future husband Park Min-hwan. Su-min's deception emerges. Ji-won cunningly responds.

Ji-hyuk gets involved in Ji-won's life for no apparent reason. Su-min organizes a reunion of former students, reviving Ji-won's school traumas. Ji-won discovers Su-min's intentions.

Ji-won attends a party with Ji-hyeok. At a school reunion, Su-min grows fixated on Ji-won after a tense meeting.

Ji-hyuk reminisces about meeting Ji-won years ago. Now his purpose is reconnecting with Ji-won. Su-min manipulates Mr. Kim to take Ji-won's proposal.

Ji-hyuk reveals his feelings for Ji-won. As forces oppose Ji-won's fate, her name disappears from the proposal. Ji-hyuk inspires Ji-won's posture as she recalls a future.

Ji-won picnics with friends before leaving them. She then reunites with Ji-hyuk, who is troubled by time travel realities he learned too late. Ji-won seems at peace while Ji-hyuk struggles.

Ji-won and Su-min, rivals at a company workshop, have an intense battle of wits with sincere confrontation. Su-min tries to hurt Ji-won's feelings. There's an incident with Min-hwan at a supermarket tasting.

Min-hwan proposes to Ji-won with Ji-hyuk's help. Ji-won spreads rumors at work. Su-min tries turning Min-hwan's mother and Ji-won into enemies to ruin the engagement dinner. The anticipated dinner arrives.

Min-hwan is ruined when Ji-won shows up, embarrassing him. Gossip says Min-hwan called off their engagement because she cheated on him with Su-min. Su-min tries to hide it, but the lies renew the supermarket scandal, trapping her.

Ji-won pursues him relentlessly as he pulls on the brakes. He opens up and they share a kiss. Su-min and Min-hwan accelerate their wedding plans due to a surprise pregnancy. Ji-won attends with Ji-hyuk, hoping to outshine the bride.

Ji-hyuk's fiancée shows up, causing conflict with Ji-won. Ji-won learns that Ju-ran has cancer and has not passed it on to his daughter Su-min. Newlyweds Su-min and Min-hwan find out infuriating information about Ji-hyuk.

After Ji-hyuk falls into a coma from an accident meant for Ji-won, she learns the truth behind it. Scared he may not wake, she confronts Su-min over memories of their shared past.

After an accident, Ji-hyuk awakens , follows the party Yu-ra is hiding. Ji-won believes getting Min-hwan to cheat will pass her fate to Su-min. She becomes Min-hwan's secret lover, fakes a breakup with Ji-hyuk and reconnects with Min-hwan.

Su-min has evidence for Yu-ra, who decides to resolve things. Ji-won and Ji-hyuk make final moves toward Min-hwan and Su-min, leading to the climax.

Ji-won receives invitation to Chairman Yu's home and plans future with Ji-hyuk. As they near happiness, Su-min, missing since Min-hwan's death, reappears, concluding the long-forged tragic fate binding the three.