Confession

Min-ho arranged to meet See-hee at the hotel after receiving a blackmail message. When he arrived, he was attacked from behind and woke up to find See-hee already dead. He allowed himself to be arrested because he had already killed See-hee two days earlier to prevent her from confessing about the Seon-jae accident. The locked room was part of his plan to appear as an innocent suspect rather than reveal his earlier crime.

The earlier flashback shows See-hee expressing guilt and contacting Young-seok to confess, setting up why Min-ho feared she would expose their crime.

Two months before the murder, Min-ho and See-hee ended their affair at his cabin. While driving away, See-hee swerved to avoid a deer, causing their car to stall. Another vehicle crashed into a boulder, killing the driver, Han Seon-jae. Fearful of exposure, See-hee convinced Min-ho to dispose of Seon-jae's car and body. Min-ho had his lawyer destroy the implicated company car and report it stolen, while Young-seok (Seon-jae's father, a passing mechanic) witnessed See-hee at the scene.

Young-seok reporting Seon-jae's disappearance and describing See-hee to police creates the initial chain of events that connects everything.

See-hee became consumed with guilt over Seon-jae's death and contacted Young-seok to confess her role in the accident. Min-ho learned of this and killed See-hee during a hotel meeting to silence her. He then staged the locked-room scenario and allowed himself to be arrested, hoping to appear as an innocent suspect framed by the real killer.

Earlier in the film, See-hee's guilt is shown through her willingness to confess, which directly triggers Min-ho's decision to eliminate her.

Yang Shin-ae is actually Lee Hee-jung, Seon-jae's mother and a retired actress. She and Young-seok kidnapped the real attorney Yang Shin-ae and staged the meeting at the cabin to trick Min-ho into confessing to Seon-jae's murder. Her goal was revenge for her son's death and to force Min-ho to admit his crimes.

The timeline shows Hee-jung and Young-seok planning together, and Shin-ae's unusual methods (lying about Hee-jung's hotel job) hint at her true motives.

Young-seok is Seon-jae's father, a mechanic who happened to pass by the crash scene. He helped See-hee in the stalled car while Min-ho went to dispose of the evidence. He later reported Seon-jae's disappearance and gave police a description of See-hee and the vehicle, making her a suspect. He conspired with Hee-jung to orchestrate the entire setup to get revenge.

Young-seok's presence at the crash scene and his subsequent report to police establish his connection to the case long before his true role is revealed.

Min-ho's stated reason was to meet with his lawyer, but his true motive was to retrieve a wrench hidden in the lake near the cabin, the murder weapon he used to kill Seon-jae during the cover-up two months earlier. He hoped to destroy this evidence before police could find it. He also wanted Shin-ae (Hee-jung) to destroy the wrench, which is why he kept insisting she retrieve it from the lake.

Min-ho's persistent requests to Shin-ae about the lake and his insistence that she find a wrench planted in the car reveal his desperation to recover the evidence.

Police recovered Seon-jae's car and body from the frozen lake beside Min-ho's cabin. This confirmed Min-ho's presence at the crash scene and exposed his lie about not being involved in Seon-jae's death. The discovery of the wrench inside the car provided the physical evidence linking him to Seon's murder.

Hee-jung realizes Min-ho came to the cabin specifically to find the wrench, confirming her suspicion about his true intentions.

The blackmail message that brought Min-ho to the hotel was connected to the Seon-jae incident, not the affair. Shin-ae theorized that someone tied to Seon-jae's disappearance sent the message to lure Min-ho out. In reality, it was part of Hee-jung and Young-seok's plan to draw Min-ho into their trap and force a confession.

The blackmail message timing aligns with Hee-jung and Young-seok's orchestrated revenge scheme.

See-hee was overwhelmed with guilt after the accident that killed Seon-jae. She directly caused the crash by swerving to avoid the deer, and she couldn't live with the burden of hiding the truth. She reached out to Young-seok to confess her role in Seon-jae's death, not knowing he was Seon-jae's father. This act of conscience ultimately led Min-ho to kill her to prevent the truth from surfacing.

See-hee's guilt is established early when she urges Min-ho to dispose of the evidence, showing her internal conflict between self-preservation and moral responsibility.

Min-ho compared the real attorney Yang Shin-ae's signature on legal documents with Shin-ae's signature from their meeting. He noticed discrepancies that revealed she was not who she claimed to be. When confronted, Hee-jung ( Shin-ae) and Young-seok were arrested, though Min-ho was also arrested shortly after as the full truth emerged.

Earlier scenes show Min-ho studying documents carefully, hinting at his suspicious nature and attention to detail.