ENA Monday-Tuesday drama 'Scarecrow' recorded its highest viewership rating in the 4th episode. It achieved 5.2% nationwide on Nielsen Korea's paid platform, reaching 5.5% in the metropolitan area and a peak of 6.2% per minute. The 2049 target rating also hit a peak of 2.1% per minute, ranking first across all channels.

In this 4th episode, the relationship between Kang Tae-joo (played by Park Hae-soo) and Cha Si-young (played by Lee Hee-joon) changed again. After the death of Kim Min-ji (played by Kim Hwan-hee), the sixth victim of the Kang serial murder case, Kang Tae-joo proposed cooperation to Cha Si-young with a strong determination to catch the culprit. Cha Si-young helped Kang Tae-joo return to duty through his older brother and police commissioner Cha Joon-young (played by Heo Jung-do).

Back on the case, Kang Tae-joo focused on the handkerchief covering the suspect's face in a photo taken by Seo Ji-won (played by Kwak Sun-young) and the scarecrow drawing found inside Kim Min-ji's art supply box near the scene of the sixth incident. Recalling the memory of meeting Kim Min-ji in front of Kang Bookstore, Kang Tae-joo headed to the bookstore, where Lee Ki-hwan (played by Jung Moon-sung) revealed that Kim Min-ji had come to retrieve the art supply box the previous night. It was also disclosed that Lee Ki-beom (played by Song Geon-hee) followed her carrying an umbrella in the sudden downpour right after she left the bookstore.

Lee Ki-beom was wanted as a suspect in the assault of Jeon Kyung-ho (played by Kang Jung-woo), and it was revealed that Kang Soon-young (played by Seo Ji-hye) was hiding him and planning to escape together. Meanwhile, Seo Ji-won suspected Lee Ki-beom, recalling that the handkerchief used by the culprit was the same as Kang Soon-young's. Jeon Kyung-ho, after seeing Kang Soon-young with Cha Si-young, followed them but was assaulted by Lee Ki-beom and fell into a coma.

At the end of the broadcast, Cha Si-young, who was chasing Kang Soon-young, encountered the culprit in the bushes, and Kang Tae-joo, arriving late at the scene, met Cha Si-young carrying a bleeding Kang Soon-young.

Additionally, part of the past connection between Kang Tae-joo and Cha Si-young was revealed. Cha Si-young had misunderstood Kang Tae-joo since witnessing his father having an affair with Kang Tae-joo's mother, and Kang Tae-joo felt deep anger and betrayal upon learning that Cha Si-young was the one who exposed his family history. The two continue their dangerous cooperation, entangled in complicated emotions and shared wounds.