Gao Bingzhu, a vice Sleuth-hound captain bottom of Luoyang, was involved in a case by mistake and became a suspect.
An informant and his daughter are murdered at the South Market. Gao Bingzhu infiltrates the Dali Temple prison, posing as a suspect to extract information and learns the informants are dead and a grand plot is underway.
Gao Sheng reports to the ruler that Gao Bingzhu, the killer in the South Market case, has surrendered. Si Yue openly points out that the case is full of doubts.
Gao Bingzhu is accused of murdering Chen Que and others. Si Yue and Pei Jian lead a team into the slums to capture him, but Gao Bingzhu willingly reveals himself.
The Dali Temple deems Gao Bingzhu a repeat killer. Gao Sheng orders all exits of the slums sealed. To save the area, Gao Bingzhu negotiates with Pei Jian, promising to find the real culprit within ten days.
Gao Bingzhu exhumes a body and deduces that Baili Yan was poisoned by venom from the Western Regions. Reviewing records, he finds anomalies in copper materials and shares this key clue with Si Yue.
By the Yi River, Gao Bingzhu and Si Yue witness Tiangou’s group swapping copper ore for relocation. Afterwards, the group plans to kill the laborers, but Si Yue rushes into the fire to save them.
Baili Hongyi realizes the marriage alliance between the Baili and Liu families is part of Liu Xiang’s scheme. Drunk, Gao Bingzhu recalls the past and breaks down, with Si Yue staying by his side.
Baili Hongyi uses a return visit with Liu Ran as an excuse to probe Liu Xiang. Meanwhile, Si Yue proposes cooperating with Gao Bingzhu.
Gao Bingzhu sneaks into the Xunshan Duke’s office and obtains the account book, but its coded text can only be read by Liu Xiang’s people. To decipher it in time, Si Yue suggests seeking help from Lianfang.
Gao Bingzhu and Baili Hongyi locate an underground copper workshop but are attacked by craftsmen. Gao Bingzhu manages to escape with Baili Hongyi.
Siyue and Baili Hongyi suspect Gao Bingzhu has gone to the Xunshan Duke’s residence. When they arrive, Liu Xiang has already taken poison and died. They blame Gao Bingzhu for acting recklessly.
Baili Hongyi and Gao Bingzhu discover a hidden weapons workshop beneath the slums. Gao plans to take Baili to meet Wang Dengcheng, but Wang’s strange behavior raises suspicion, so Gao hints that Baili should seek reinforcements.
In a ruined mountain temple, Gao Bingzhu finds Wang Dengcheng, his unconscious mother, and Si Yue bound. Wang tries to recruit Gao into Chunqiu Dao, and when he refuses, forces him to choose between his mother and Si Yue.
Si Yue receives an invitation from Princess Changle. The Prince of Jin oversees Song Liang’s case, while the Crown Prince, fearing implication, seeks Si Yue’s help to prove his innocence to the ruler.
Gongzi Chu asks Gao Bingzhu to escort Wang Dengcheng from Dali Temple to Lianfang, but Wang is killed midway by Shiliuye. Baili Hongyi notices Liu Ran secretly following and takes her along to Lian Mountain.
Gao Bingzhu discovers that Ruo’an communicates with informants through coded signals using pottery and food. Reporting this to Gongzi Chu, they expose the spy and decide to root out the traitor within Lianfang.
After returning to the capital, Baili Hongyi arranges to meet an official at Liubai Tower. Shiliuye reports this, and is ordered to learn the details and then eliminate Baili Hongyi.
Si Yue decides to personally watch over Baili Hongyi, with Li Beiqi staying to assist her. Gao Bingzhu compiles a list of suspected traitors and interrogates them one by one, causing discontent within Lianfang.
Si Yue tells Gao Bingzhu that Shiliuye may be a woman. Baili Hongyi causes trouble at the Internal Guard office correcting errors, annoying everyone. Li Beiqi detains him in the guard’s jail.
Yao Niang commits suicide in front of Gao Bingzhu, leaving him devastated. Si Yue accompanies him to a coffin shop to drink. Meanwhile, Baili Hongyi finds Kang Zhanbi’s body at Guangling Inn.
Gao Bingzhu regains his resolve and returns to Lianfang to investigate Chunqiu Dao, determined to eliminate the threat at its source.
Baili Hongyi gives Si Yue a portrait of Kang Jin based on Liu Feng’s description. Si Yue seeks help from Lianfang. Gao Bingzhu and Si Yue enjoy the lantern festival together, while Baili gifts Liu Ran a small portrait for Qixi Festival.
A neighbor lies, but Si Yue notices clues and tracks down Kang Jin. Gong Yan suddenly appears to assassinate him. Si Yue chases her, leaving Li Beiqi behind to guard.
The trio suspects the Eastern Palace is linked to Chunqiu Dao and plans to investigate. The Crown Prince avoids them, so Si Yue seeks help from Princess Changle. When questioned, the Crown Prince denies everything, but an explosion occurs inside the palace.
The Crown Prince finally reveals the truth. Si Yue brings back a lead on Dai Zhou, a gambling addict. Gao Bingzhu and Bailang head to a gambling house to find him.
Si Yue rushes to the gambling house and rescues the unconscious Gao Bingzhu, revealing her true feelings out of concern. Liu Ran is kidnapped by Tiantong Daoist while helping Baili Hongyi.
Gao Bingzhu sends a dish tied to shared memories with Baili Hongyi to pass a message. Realizing help has come, Baili Hongyi requests to meet Tiantong Daoist.
Gao Bingzhu and Si Yue are rescued by the Internal Guard, while Si Yue is taken back to their headquarters. Gao and Baili suspect Chunqiu Dao is developing weapons of mass destruction.
Gao Bingzhu orders Lianfang to inspect suspicious goods entering the capital and deduces Chunqiu Dao’s target is the Lantern Festival ceremony. As it cannot be canceled, he seeks clues from Xiaoyaozi at the Internal Guard.
Gao Bingzhu decides to go alone to find Chunqiu Dao’s base, but Bailang insists on going with him. Evidence points to Li Beiqi as a member of Chunqiu Dao, leaving Si Yue devastated and unwilling to believe it.
Baili Hongyi inspects security for the Internal Guard, but they show little respect and work carelessly. He firmly explains the destructive power of Fuhuo Thunder and the importance of their duty.
As the Lantern Ceremony begins, the ruler attends in full regalia. Baili Hongyi successfully prevents an explosion, but Shen Fei is killed by an arrow while protecting him.
Pei Jian arrives to arrest Gao Bingzhu, who is deemed a suspect due to his presence at the explosion site. Wu Youjue steps forward to defend him.
