Song Na attempts to assassinate Chi Xiao, but at the critical moment, she softens and hesitates, only to be subdued by Chi Xiao and left unconscious with a head injury. After discovering that she is an elite assassin, Chi Xiao initially intends to eliminate her. However, when Song Na awakens, she has lost her memory. To keep her under better control, Chi Xiao has her join the Chi family as his personal bodyguard. As they spend time together, they gradually discover that they are the orphanage companions they have both been searching for for years. The two souls who once saved each other find their way back to one another once again...