The Heir: Killing the Prince from the Start Is Only Reasonable

Year 844 of the Great Qian dynasty. Lin Guoyu is an undercover agent in the prince's residence. He can only watch as a ruthless killer poisons and knocks everyone unconscious, then cuts down every last person in the Prince of Yongan's residence, leaving only him alive. An undercover agent posing as the prince's illegitimate son, he has no chance of seeing the killer's true face. That night, the Qian Emperor sends the Chief Commander of the Mirror-Wielding Bureau to question him. “Lin Guoyu, you're pretty quick with a blade!”