Reviewers found the ending of Episode 4 particularly heartbreaking, as it concludes with the discovery of the body of Shi-woo, the protagonist's son.

“Trap certainly caught me by surprise since I did not expect this high energy and fast-paced thriller. ... The intensity of all the actors blended so well together that each small gesture of movement spoke volumes.” hellokpop · 7 years ago

The episode is noted for its high-energy, fast-paced thriller elements. A significant moment occurs when Seo-young takes a risk by calling a burner phone while under CCTV surveillance by Won-tae.

Detectives Ko Dong-kook and Yoon Seo-young intensify their investigation by heading to the main character Woo-hyun's house, where they believe secrets are hidden.