MBC's 'Married Woman Killer' hits 9.4% in episode 4, peaks at 10.9%

Episode 4 of MBC's 유부녀 킬러 (Married Woman Killer) pulled 9.4% viewership on August 8, the show's best number yet. The Seoul metropolitan area landed at 8.9%.

The growth has been consistent. Episode 1 started at 7.4%. Episode 2 climbed to 8.0%. Episode 3 hit 8.3%. Episode 4's jump to 9.4% marks a 1.1 percentage point rise from the week before.

One scene spiked the ratings further. When Kim Bong-pal (Sung Dong-il)—a former Army Special Forces member—walks Oh Hyun-nam (Ha Yul-li) through how to handle criminals targeting children, the peak minute rating reached 10.9%. The 20–54 demographic scored 3.3% for the episode, ranking first across all programs that day and holding the top spot in that metric for a second consecutive week.

The episode's plot: over 15 years, eight child sex offenders all died in accidents on their release dates. Yoo Bo-na (Gong Hyo-jin) directly confronts and eliminates a child sex offender who flees after release. She and her husband Kwon Tae-seong (Jung Jun-won) are also receiving threats from an unknown source—though what they drank turns out to be a sleeping pill, not poison.

A hidden backstory between Yoo Bo-na and Oh Hyun-nam surfaced, tied to a Kingfisher sniper incident from 15 years ago on Christmas. Oh Hyun-nam tells Yoo Bo-na: "You're my Santa, the savior of my life. I want to go back to the old Kingfisher." The show's moral debate runs sharp. Lee Dong-jin (Lee Sang-i) argues that murder cannot be justified under any circumstances and no individual has the right to judge others outside of social agreements.

The workshop at Tae-gong-san Grandpa's Pension was a planned operation by Sales Team 3 targeting an organ trafficking organization's hideout.

The end-of-episode preview showed Yoo Bo-na clashing with her in-laws and moving to handle a new case.

유부녀 킬러 is written by Kim Eun-hee and directed by Yoon Jong-ho and Kim Ji-hun. 14 episodes total. Streams on Wavve and Coupang Play.