Jeongseo and Songju have been each other's solace since childhood—best friends and first loves bound by an unspoken promise. After losing her mother, Jeongseo’s life takes a darker turn when her father remarries. She is forced to live under the same roof as her cold stepmother Mira and jealous stepsister Yuri, who resent and abuse her at every turn. While Songju, the son of a powerful conglomerate chairman, cherishes Jeongseo with genuine love, Yuri becomes obsessed with him, determined to tear them apart no matter the cost. As their bond deepens, so does the malice surrounding them. In a world where jealousy festers and cruelty is masked by elegance, Jeongseo and Songju’s innocent love stands fragile—threatened by the very people meant to be family. Their story begins with warmth, but fate seems poised to lead them into tragedy.