Episode 8 of "Nine Puzzles" kicks off with Cheol-jin embarking on a yacht journey in the scenic backdrop of Jeju Island. The scene transitions to him dozing peacefully in the middle of the vast, open sea, until an unexpected visitor stirs him from his slumber, causing him to jump with alarm.
Meanwhile, the Hangang police are informed about I-na's arrest. Her nonchalant and mischievous demeanor persists as she remains tight-lipped, leaving Han-saem utterly frustrated. Even Captain Yang and Chief Hyun arrive on the scene, offering their assistance, but I-na finds it peculiar that Yang is advocating for her innocence.
To everyone's surprise, Dr. Hwang and Dr. Lee are also in Jeju for Dr. Hwang's seminar on the themes of darkness and retaliation. Han-saem reaches out to them, and they arrive, hoping that I-na might open up to them. Instead, I-na merely hands the latest puzzle piece to Lee, who then passes it to Han-saem. The piece depicts a man participating in a burger-eating competition.
Han-saem again confronts Yang, inquiring why he didn't mention the puzzle at the crime scene of Reporter Lee. Yang replies that he didn't trust Han-saem due to his closeness to I-na and continues to insist that she's hiding something.
Frustrated and at his wits' end, Han-saem pleads with I-na to help him understand her motives, but she continues to act playfully. However, she eventually gives him a clue for her alibi - the taxi service. The murder occurred between 5 pm and 8 pm, and I-na had left the yacht at 5 pm. While stopped at a red light, she received the puzzle piece..
Once I-na's name is cleared from suspicion, she unveils her meticulously crafted plan to Han-saem. For too long, she has been manipulated by the killer, but now, she intends to seize control of the game. She deliberately framed herself for Cheol-jin's murder, knowing that the killer prefers her alive and unharmed for his twisted amusement. Consequently, anyone who attempted to assist her must either be the killer themselves or closely associated with them. The circle of suspicion tightens around Chief Hyun, Captain Yang, Dr. Lee, and Dr. Hwang. Han-saem mentions that he also brought Choi San along to Jeju.
Back in Seoul, I-na confronts Dr. Lee about her unexpected presence on the island. Sensing her role as a suspect, Lee plays along cunningly. I-na finds it perplexing that Lee has been so engrossed in her complex case for a decade. Lee casually responds that she sought to outperform I-na's previous therapist, Dr. Hwang, who failed to provide any significant help. As I-na prepares to leave, she sneaks into Dr. Hwang's office, seeking clues.
Meanwhile, Han-saem begins scrutinizing the suspects, starting with Captain Yang. He speaks with Yang's former partner at the Mapo precinct, uncovering a shadowy figure – a man of mystery and aloofness. During their sole drinking session, Yang abruptly left, claiming his sibling was in distress. Yet, Yang is an orphan with no siblings. It was the same night Dong-hoon was killed, and upon his return, Yang was soaked through with rain.
The stakes rise as Han-saem learns that the bar they frequented was Jinhui Bar, situated at the crossroads leading to Dong-hoon's residence. A chilling realization dawns: Yang could have taken the shortcut and arrived at Dong-hoon's before I-na.
Chief Hyun officially assembles a task force dedicated to the puzzle killer case, assigning Dong-su to lead it. I-na briefs them on the six puzzle pieces, the intricate connections between the murders, and the ominous prophecy of three more deaths to complete the grim mosaic.
After work, Han-saem and I-na share drinks, delving into the enigmatic Captain Yang and the possibility that he might be the elusive puzzle killer. Han-saem, citing his favorite film "LA Confidential," engages in playful banter with I-na, who admits she hasn't seen it. She then recounts her fateful encounter with Cheol-jin, adding another layer of complexity to their ongoing investigation.
A flashback unfolds, revealing I-na confiding in Cheol-jin about the enigmatic puzzle killer. Given his oversight of The One City construction, Cheol-jin harbored a grim certainty that he was the killer's next target. He casually mentioned the Yoons, startling I-na as he revealed his closeness to her parents. He further remarked on the expected bond between her and his son, Yeong-hun.
Prior to the subsequent briefing, Han-saem confided in Dong-su, whispering his suspicions towards Yang. The police gathering soon after brought dire news: Cheol-jin had been choked to death. Yang observed Han-saem's absence and Dong-su's evasive demeanor with concern. Aware that Han-saem was onto him thanks to his Mapo informant, Yang remained undeterred, vowing to uncover the killer.
He then sought out I-na, probing her about her rooftop vantage point during Reporter Lee's tragic demise. She deceived him, prompting him to bide his time until she confessed the truth. Matters grew grimmer for Yang as flight records implicated him, placing him in Jeju a month prior and again on the fatal day of Cheol-jin's demise. Desperation clawed at Han-saem, leading him to enlist I-na's superior to hypnotize Choi San. As anticipated, Choi San's repressed memories resurfaced, depicting Yang surreptitiously pocketing the missing handkerchief from Yoon-su's crime scene.
In the cliffhanger of Nine Puzzles Episode 8, Han-saem burst into Yang's presence, who, in a dramatic gesture, produced the incriminating handkerchief.
