Shen Mingshu is extremely afraid of dying. Born into a prestigious censor's family renowned for producing loyal martyrs, she digs underground escape tunnels and stockpiles supplies so she can flee at a moment's notice. When the true daughter, Shen Aoxue, arrives with a blood-written letter, a blood test confirms their relationship, but the entire family forcibly insists that Mingshu stay. During a palace banquet, Mingshu instinctively kills an assassin in self-defense, only to be bestowed the title of Chaste and Heroic Princess by the emperor, effectively trapping her in the capital. After the emperor stages an assassination attempt and arranges a marriage to drive the Shen family to their deaths, Mingshu initially plans to escape alone. But when she sees Aoxue standing alone to shield the family from a blade, she finally turns back to save them all and expose the emperor's conspiracy to replace his daughter and use the Shen family's loyalty against them.