Crown Prince: It Makes Sense to Kill the Prince at the Beginning, Right?

Daqian 844. Lin Guoyu is undercover in the prince's mansion. He watched helplessly as the murderer poisoned everyone and killed everyone in Yong'an Palace with one knife, leaving only him. He, an undercover agent pretending to be the illegitimate son of the royal family, had no chance to see the murderer's true face. At night, Emperor Qian sent the chief inspector of the mirror department to come to ask questions. "Ling Guoyu, your knife is very fast!"