Plot
Following the events of Mrs. Cop, Park Jong-ho (Kim Min-jong) of Seoul Metropolitan Police Agency planned to fill in Crime Squad Team One since its leader Choi Young-jin (Kim Hee-ae) left and the rest of her team followed suit. The head of police recommended Ko Yoon-jung (Kim Sung-ryung) to be the new leader. She has just returned to South Korea from New York after 6 years wherein she trained with the F.B.I.. She intended to reopen the Bundang female college student murder case that she solved in 2010 because she discovered that the imprisoned culprit Min Jong-bun (Kim Byung-chul) is actually innocent. As the new team captain, she formed the new Crime Squad Team One composed of Bae Dae-hoon (Lee Joon-hyuk), Kang Sang-chul (Kim Hee-chan), Oh Seung-il (Lim Seul-ong), and Shin Yeo-ok (Son Dam-bi).
The first assignment of the team was the Jung Mi-ryung murder case in which CEO Lee Ro-joon (Kim Bum) of EL Capital is the principal suspect. After an in-depth investigation, Yoon-jung deduced that this is not a standalone case but rather a serial murder case that took place every March 15 for the last 6 years (from 2010 to 2015), starting with the Bundang female college student murder case. In turn, she ruled out Ro-joon as the suspect since he was not in the country until 2011. However, she suspected Ro-joon to have pertinent info about the case so she pursued him. She was tricked into a deal with Ro-joon to exempt him from the reinvestigation in exchange for the info about the real criminal. Eventually, his tip helped Yoon-jung and her team capture the real culprit Kim Ha-ram (Seo Young).
Next, the team decided to take on the case of pickpocketing which Jong-ho and Detective Jung frowned upon. While looking for intel, they discovered a lead to the big-time swindler Joo Hee-chul (Lee Jae-yong) instead. After two undercover missions, they caught the swindler and his group in an armed operation.
Yoon-jung discovered EL Capital's investment in Hee-chul so she met with Ro-joon personally to question its validity. As she was leaving their meeting place, she stumbled upon the case of Ha Sung-woo's (Yoo Jang-young) disappearance. Not long after, they found Sung-woo's corpse in a river. After meeting with the sole witness Lee Hae-in (Jang Seo-kyung), she confirmed her suspicion that Ro-joon is the murderer in this case. They arrested him with Director Baek Jong-shik (Choi Jin-ho) as his accomplice. However, Hae-in appeared to have attempted suicide before testifying in the trial. Without a witness, the murder case had no evidence to proceed. Through Yoon-jung's keen insight and Ro-joon's confession, it is revealed that he staged her suicide through coercion and betting in a game. However, this case could not be proven as Yoon-jung's attempt to record Ro-joon's confession failed. Since Hae-in is in critical condition and unable to testify, the prosecutor did not appeal the case. Therefore, Ro-joon was found innocent for now.
In the meantime, the Seoul Metropolitan Police Agency set an operation to capture the Gangnam gangster group that controls illegal drug markets across the country. They succeeded and arrested all gang members except for two. Upon further inquiry, it turned out that the missing members were killed by Ro-joon in self-defense when he was attacked by the gang. Though they wanted to prosecute him, the murders were valid on the basis of self-defense.
Next, Yoon-jung and her team take on the suicide case of Cha Seul-ho (Kim Hak-seon) whose body was found in Dong Woo University Hospital. Recently, his daughter suffering from a rare disease died in the same hospital due to alleged medical malpractice. However, they discovered that Seul-ho committed suicide at EL Capital and Jong-shik dumped his corpse in the hospital. Their investigation culminated when Seul-ho's will was recovered through pressure mark analysis. It is revealed to the public that EL Capital staged the medical malpractice allegation in order to accelerate the sale of the hospital to the company. As a result, the sale did not proceed, the scandal damaged the company's image, and Jong-shik stepped down as director to take all the blame. This marked the start of Ro-joon's downfall.
Meanwhile, Ro-joon's adversary Director Park Joon-young (Lee Chul-min) is on the move to oust him and be the new CEO given the current circumstances. Previously, Joon-young ordered six Gangnam gangster group members to kill Ro-joon. Knowing this, Yoon-jung offered Joon-young to spy on Ro-joon and was eventually convinced by Jong-ho to do so. In addition to Ro-joon's mounting problems, his mother Seo Jung-mi was arrested for bidding in an illegal auction of stolen artworks. The police issued a search warrant to find more stolen artworks in Jung-mi's house. While searching, they found the letter of Ro-joon's late father Lee Bong-jun which states his intention to return his money and properties to society. The police also cracked down the storage room at Attirance Gallery full of stolen artworks and artifacts. Those collections are owned and inherited by Ro-joon from his father.
Given the circumstances, Ro-joon lacked funds for lobbying the government to establish hospitals for profit. He then ordered to smuggle 50 billion won from the cash reserves of EL Capital disguised for supplying the shortage in their branches. Director Park tipped Yoon-jung that this is a suspicious and unusual amount of money withdrawn. The police pursued the van carrying the money and the latter even attempted to mislead them by changing its label. However, Yoon-jung figured out this change and continuously chased the van until it met an accident and got burned along with the cash it carried. In a desperate move, Ro-joon borrowed 30 billion won in cash with high interest from a private moneylender just to pursue lobbying for his project.
On the other hand, Yoon-jung and her team handled the murder case of Im Min-son in which Lawyer Seo is the primary suspect. Lawyer Seo thought he was the cause of Min-son's death so he blackmailed Director Park to cover it up for him. Two years ago, Lawyer Seo handled Lee Bum-jin's will to return his money and properties to society but Director Park took the original copy. However, he kept a soft copy of the will. In the present, Director Park sent someone to kill Atty. Seo instead but he escaped. He approached Ro-joon for help but ordered his men to lock him up. He escaped and planned to surrender to the police. However, he was chased by Jong-shik's men and Yoon-jung and her team on a highway until he met a fatal accident. Upon dying, he gave the copy of the will in a memory card to Yoon-jung. Meanwhile, Yeo-ok and Yoon-jung figured out the real murderer was Yoo Ok-im, Im Min-son's housekeeper.
In the shareholders' meeting, Director Park was declared as the new CEO with the deciding vote coming from Jung-mi. She voted for him in exchange for the evidence that Ro-joon killed his own father because of his decision to return his money and properties to society. On one hand, Yoon-jung used the will to blackmail CEO Park to reveal Ro-joon's weakness. He told her about the doctor who was the sole witness of Bum-jin's murder. Meanwhile, Hae-in was already recovering so the police transferred her to a safe place in the countryside. While accompanying her, Yeo-ok found a bloodstain on the sweater worn by Hae-in on the day of the crime. She confirmed her suspicion that it was Ro-joon's blood. This physical evidence enabled them to issue a warrant of arrest against Ro-joon. They arrested Ro-joon after another shareholders' meeting in which he was re-elected as CEO after Director Park's disappearance. Before this, Director Park was shot dead by Director Baek on Ro-joon's order right before his inauguration. Ro-joon was detained but was able to escape while disguising himself as a cop.
In a last attempt to kill Yoon-jung, Ro-joon kidnapped Seung-il so that Yoon-jung will come to save him. This confrontation backfired as Jong-shik was fatally wounded and killed himself instead, allowing Ro-joon to escape. He attempted to escape the country to Brazil with former chief justice Kang but was cornered by the police in hot pursuit. He was successfully arrested and was later sentenced to death. On the other hand, Yoon-jung and her team were honored for their brave services. They continue with fighting crimes daily, believing it would someday lead to a fair world.
