Han Yeol Moo is a new apprentice prosecutor under Koo Dong Chi's supervision. Though they have a past together, they try to prevent it from getting in the way of the case at hand: capturing a perverted flasher and a child molester.
A case of assault and fraud for Han Yeol Moo reunites Kang Soo and Dong Chi with an old friend, and leads to bigger fish for the team to catch: a drug ring.
Dong Chi sees through Hee Man's desire to close the child abuse case longer, and manages to get an extension for a re-investigation. Yeol Moo gets a piece of evidence that is related to her brother's death.
Moon Hee Man tasks his team to investigate a corruption case that might have negative ramifications on his team. Dong Chi helps reopen Yeol Moo's brother's case, which raises more questions than answers.
Yeol Moo and Dong Chi discover more about Kang Soo's past, which is connected to Han Byul's death. The team must find a new way to tackle a murder case when all the suspects have been released from detention.
Dong Chi's reassignment reveals the dangerous power game Chief Moon must play while using his team as his pawns. The case with Joo Yoon Jang finally leads to an arrest.
The race is on to find incriminating evidence against Joo Yoon Jang. Dong Chi is given a recording that connects Moon Hee Man to Kang Soo and Han Byul's case from years ago.
The public welfare team is on the verge of disbandment, so Dong Chi and Yeol Moo are on the race to find more evidence and formally charge Moon Hee Man and Jung Chang Gi. An unlikely ally comes forward with more evidence to help their case.
Seeing that the evidence is coming together too easily, the team is on the hunt for the real mastermind of the kidnappings, not believing that Chief Moon could have done it. Meanwhile, Deputy Oh disbands the team.
Dong Chi manages to buy some time before he must be indicted, and tries his best to protect Song Ah Reum, the one key witness who can reveal everything.
Han Byul's case goes to court and the team finds themselves going up against the formidable Park Man Geun. But Hwa Young and Park Man Geun may prove to be too strong for the team to handle.