Four years ago, the legendary commander Yurin disappeared after ending a devastating war in only nine days. The empire mourned her as a fallen hero, while the enemy kingdom quietly searched for a lost princess believed to have died years ago. No one knows that both women are the same person. Now living under the name Kang Shuishui, she has spent four lonely years as an overlooked imperial concubine. Her emperor husband has never shown her affection, attention, or even the slightest interest in her existence. She has learned to accept it. Until the emperor returns from war. And with him comes Prince Yin. Yin is everything Shuishui has spent years trying to forget—kind, gentle, impossibly patient, and beloved by everyone around him. But there is something even more dangerous about his return: the feelings she thought she had buried begin to surface again. As strange incidents begin disturbing the imperial court, an escaped enemy commander, secret messages, palace conspiracies, and growing tensions between two kingdoms threaten to expose buried truths. Then Shuishui's carefully constructed life begins to unravel. The woman the empire remembers as a dead commander. The woman Yin once loved. The forgotten concubine living inside the palace. And the lost princess of the enemy kingdom. They are all one person. But that is only the first secret. Because the war that changed both kingdoms was built upon a lie—and the truth may destroy far more than an empire. In a palace where everyone has something to hide, falling in love may be the most dangerous secret of all.