Harin and Dohyeon are two lovers whose happiness is cut short when Dohyeon falls ill. In a desperate attempt to save him, Harin is offered 1000 lifetimes to prove their love by a witch, but with a catch - Minji, the witch's daughter, also loves Dohyeon and will do everything she can to stop them. Throughout 999 lifetimes, Harin fails, and Dohyeon ends up with Minji for the 999 times. In her last life, Harin is in the 21st century. Dohyeon is now the CEO of Harin's company, where she works, and Minji is his soon-to-be fiancée and co-CEO. With one lifetime left, Harin is determined to finally succeed in proving her love.