To fund her sister's medical care, the elite nanny joins the wealthy family to "fix" the second son's romantic tastes. Instead, she heals his trauma and unites the fractured siblings. As she tries to leave, his obsessive pleas and a clue about her sister's attacker pull her back. Soon, the eldest son begs her to be his fake fiancée to dodge a royal stalker. With all four brothers falling for her, can they shatter high-society rules to protect the woman they love?