One day, Ha Na wakes up to find herself in the world of a romance novel—as the first fiancée of the male lead. The problem? Her character is a minor one destined to be poisoned at the engagement party of Cheon Nam Ju, heir to the Cheonnam Group. To avoid her tragic fate, Ha Na proposes a contract marriage to Park U Jin, the notorious "tyrant" and acting chairman of the rival Samjeong Group. U Jin accepts the offer, and Ha Na's destiny begins to veer in an unpredictable direction.