My Lady General S1 E16

In order to redress the injustice of late Crown Prince, Wei Lin, the Chief Commander of Zhangluan Army, a rough and illiterate female general, marries Gu Ming Zhu, the handsome sickly son of Gu Cheng Yuan. But Ming Zhu turns out to be an imposter and is actually Jiang Juan, the new leader of Ling Pavilion, an assassin organization. He is in cahoots with General Wei's enemy, the 2nd Prince of Qingyue. Jiang plotted his admission into General Wei's mansion to steal her "Yan Yu" to detoxify the poison in him...