Do Hae-Kang, a brilliant but emotionally distant lawyer, watches her perfect life shatter after the tragic loss of her daughter. Her husband Choi Jin-Eon, heir to a powerful pharmaceutical corporation, turns cold and seeks comfort in an affair, cruelly demanding a divorce. Broken yet composed, Hae-Kang signs away her past, only to have her world further upended when a near-fatal accident erases her memory leads to a switch of fates with her long-lost twin sister Dokgo Yong-Ki’s life. Mistaken for Yong-Ki, her separated-at-birth twin, Hae-Kang is taken in by Baek Seok, a kind lawyer who believes she is his first love. As fragments of her past resurface, she is drawn back into Jin-Eon’s orbit, reigniting a dangerous affair that forces her to confront painful family secrets and a haunting truth that could change everything.