Nirvana in Fire Episode 12

Mei Changsu meets Master Zhou, and the two talk about Official Li, a past imperial tutor who taught Lin Shu. After Master Zhou leaves, Princess Nihuang confronts Mei, and correctly deduces that Mei is Lin Shu, her past fiance, which brings her great joy. Meanwhile, Shen Zhui meets Prince Jing in the streets of the capital, and together they investigate the canal ports. Shen Zhui explains to the prince that the ship's cargo should not weigh as much as it's supposed to, causing him to believe that the ship is smuggling gunpowder. Tong Lu investigates and discovers an illegal fireworks factory that is run by the Crown Prince; Mei has the information given to Shen Zhui. Coincidentally, the Empress becomes ill, but as it is not life-threatening, Mei suspects someone is behind the illness. (Source: Wikipedia)