9 timestamped notes explaining the Korean cultural context in this episode — customs, idioms, food, honorifics, and history, at the moment each appears on screen. These notes discuss events across the whole episode. To see them revealed scene-by-scene as you watch, use the episode page to find an airing.
Korean media gave serial killer Han Seo-jun the nickname 헤드헌터 (headhunter), a direct English loanword flipped into dark irony — he literally collected his victims' severed heads. Giving serial killers dramatic nicknames in news coverage is common in Korea, echoing the tabloid-style crime reporting culture audiences would instantly recognise.
A bystander says the woman took pills intending to die together with her unborn child — this is 동반자살 (donban jasa), a suicide pact or joint suicide. The concept carries particular cultural weight in Korea; a parent taking a child along is viewed as one of the gravest moral transgressions, hence the furious reaction from onlookers.
Detective Mu-chi refers to Han Seo-jun having already received a death sentence (사형, sahyeong). South Korea retains capital punishment on its books but has not carried out an execution since 1997, making it a de facto abolitionist state — which is exactly why Mu-chi is furious that a condemned man is still 'eating and sleeping just fine.'
Ba-reum quotes 눈에는 눈, 이에는 이, the Korean rendering of the biblical lex talionis ('an eye for an eye, a tooth for a tooth'). It lands with extra weight here because he immediately follows it with a direct personal threat — he is framing his warning in the language of Old Testament justice, not mere neighbourhood conflict.
The vet asks whether the dog was given anything containing 자일리톨 (xylitol), a sugar substitute found in sugar-free gum, candy, and some baked goods that is highly toxic to dogs even in tiny amounts, causing a rapid blood-sugar crash. Korean pet owners are widely warned about this, so the vet's question immediately signals to a local audience that someone fed the dog something deliberately.
Woo Hyeong-cheol mockingly asks whether the two detectives are the 그림 형제 (Grimm Brothers), calling their reconstruction of events a fairy tale. Referencing the famous German storytellers as shorthand for 'that sounds made-up' is a common, slightly literary put-down in Korean conversation.
강덕수 (Gang Deok-su) is a convicted child sexual abuser from the neighbourhood who has just been released from prison. The news that he has returned to his mother's house sends immediate panic through the community — families with children have already moved away. In Korea, released sex offenders are listed on a public registry (성범죄자 알림e), but many communities feel the notification system does not protect them adequately.
Woo Hyeong-cheol claims the binding knot that killed Jeong Su-jin was tied during a 보이스카우트 (Boy Scout) rope-craft drill gone wrong. The Boy Scout organisation (한국 스카우트 연맹) is well-known in Korea for teaching 산악 구조용 매듭 (mountain rescue knots), so the excuse sounds plausible enough that his grief-stricken father wanted desperately to believe it.
Woo Hyeong-cheol reveals that the late Dr Daniel Lee told him he was born a 사이코패스 (psychopath) — a callback to the series' central premise about a prenatal gene test for predatory psychopathy. This confirms he was one of Daniel's identified subjects, tying his killing spree directly to the show's ongoing debate about whether such a diagnosis is a sentence or a choice.