Season 1
Cha Ju-hyeok works at a bank and has been married to Seo U-jin for five years. When a strange incident happens one day, Ju-hyeok makes a decision that impacts his life and those around him in unexpected ways. Suddenly, the life he had with U-jin and his best friend, Yun Jong-hu, is gone, and he is leading a very different life. How will his first love, Lee Hye-won, factor into his new life? And will it be possible to get his old life back?
Episode 1
Cha Ju-hyeok and Seo U-jin lead an unhappy marriage as busy working parents. One day, Ju-hyeok is handed something special.
Episode 2
Ju-hyeok secretly buys a new video game console knowing that he's dead if U-jin finds out. Later, he returns to the mysterious toll booth.
Episode 3
Ju-hyeok wakes up in a different house and lying next to a different wife. U-jin picks up a stranger's phone and tries to return it.
Episode 4
When U-jin begins her new job at the bank, Ju-hyeok tries to have her transfer to another branch. Lee Hye-won's behavior upsets Ju-hyeok's parents.
Episode 5
Meeting U-jin's mother startles Ju-hyeok, who finally learns about her condition. At the bank, U-jin is put in a potentially dangerous situation.
Episode 6
After confessing his feelings to U-jin, Yun Jong-hu volunteers to join her on an overnight work trip. Horrified, Ju-hyeok follows them.
Episode 7
A surprise visitor comes to the bank looking for Ju-hyeok. The three friends agree to go on a getaway together with their partners.
Episode 8
Ju-hyeok wants to return to the way it was, but it may be too late. When her mother goes missing, U-jin is overcome with worry.
Episode 9
Finding out about Ju-hyeok's lie infuriates Hye-won. Meanwhile, a malevolent post is written about U-jin on an online community.
Episode 10
After a fight with Ju-hyeok, Hye-won takes drastic action. U-jin and Jong-hu's co-workers find out about their relationship.
Episode 11
U-jin has something to say to Jong-hu, who later overhears a conversation that stuns him. Hye-won sees the real Jung Hyeon-su.
Episode 12
The truth about her unusual connection with Ju-hyeok becomes clear to U-jin. At work, a sudden emergency places Ju-hyeok at risk of losing his job.
Episode 13
Finding himself back in 2006, Ju-hyeok tries all he can to avoid U-jin. When they wake up in the present, life has changed again.
Episode 14
To Ju-hyeok's distress, U-jin returns to the bank. While she wants to make things work, he remains adamant about pushing her away.
Episode 15
While sneaking around their co-workers on a date, U-jin runs into her charming first love from her university days and makes Ju-hyeok jealous.
Episode 16
Three years later, Ju-hyeok and U-jin have come full circle — with revisions. Hye-won shows up at a university club reunion.