Ep 7. Episode 7

Detective Park Kwang-ho and his team are still hot on the trail of the serial killer who has been plaguing the city for months. As they investigate further, they discover a link between the victims that they hadn't noticed before: they were all members of the same church. The detectives suspect that the killer may have some sort of vendetta against the church, but they don't know what exactly.

One of the victims, a young man named Lee Sung-jae, had been the pastor of the church before he was brutally murdered. Detective Kwang-ho visits the church to talk to some of the other members and learn more about Sung-jae. He meets a woman named Kim Hwa-jung, who used to be close with Sung-jae before he died. She tells Kwang-ho that Sung-jae had been struggling financially, and that he had been involved in some shady business deals that might have something to do with his death.

Meanwhile, the killer strikes again. This time, the victim is a young woman named Kim Min-jae. The detectives are able to find some DNA evidence at the crime scene, which leads them to a suspect: a man named Jang Woo-sung. They bring him in for questioning, but he denies any involvement in the murders.

Kwang-ho and his team keep digging, and they discover that Woo-sung had been a member of the same church as the other victims. They also find out that Sung-jae had been involved in a scam involving a phony investment scheme. It turns out that Woo-sung had invested a lot of money in that scheme, and he lost everything when it fell apart. The detectives suspect that Woo-sung might be seeking revenge against the people he thinks are responsible for his losses.

As they investigate further, the detectives uncover more and more evidence linking Woo-sung to the murders. But then they receive a mysterious phone call from someone claiming to be the real killer. The caller tells them that they have the wrong man, and that the real killer is still out there.

With this new lead, Kwang-ho and his team race against the clock to catch the real killer before they strike again. They follow a trail of evidence that leads them to a shocking revelation about the killer's identity.

Episode 7 of Tunnel is a tense and thrilling chapter in the series, as the detectives inch closer and closer to solving the case, but also face unexpected twists and turns along the way. With strong performances from the cast and clever writing that keeps the audience guessing, this episode is a standout in the first season of the show.