After Shen Tangning was reborn, she was forced to marry into the regent's palace for her sister-in-law, but found out that the sick prince Xie Xuanjin was not sick at all - he was pretending to be sick. The two reached a cooperation through mutual testing: she investigated an old case in which her mother was killed by a drug test, and he investigated the mastermind behind an old injury case in the North. The same poison recipe and the same knives of the palace guards tied two lives into a rope. From trading allies to holding swords together, she asked the prince's mansion to pay for her life and the palace to pay for her life; his life was hers from now on.
