Living a lie as an ordinary woman, Sun-jung—a psychopath—finally feels her heart flutter for the first time. Is it love, or is it obsession? At the thin line between love and her lethal instincts, Sun-jung’s twisted romance begins!

After secretly marrying Min Woo-bin, Kang Ji-won hides her identity as his wife and the world-famous designer ""Summer"" to join the company as an ordinary employee. Lee Yun-ju targets her and tries to claim the title of being the CEO's wife. Even Woo-bin's mother turns against Ji-won due to rumors. Meanwhile, Woo-bin's younger brother unknowingly falls for Ji-won. At a major fashion launch, Yun-ju steals Ji-won's designs. How will Ji-won handle all these challenges?