12 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.
In South Korea, polygraph (거짓말 탐지기, literally 'lie-detector') results can be used as investigative reference, though not as court evidence. The drama taps into a widely held popular belief — reinforced by true-crime media coverage — that psychopaths don't register stress responses on polygraphs because they genuinely feel no anxiety about lying. This idea was debated publicly during several high-profile serial-killer cases in Korea.
The news broadcast refers to a fictional 'Headhunter' (헤드헌터) murder case, 20 victims, 25 years earlier — framed as the defining national trauma of its era. Korean audiences would read this as a nod to real cold cases that gripped the country, most famously the Hwaseong serial murders (1986–1991), which went unsolved for decades and reshaped public debate about policing and criminal psychology.
The character presses a needle to someone's neck and explains that the carotid artery (경동맥) runs right there — if pierced, blood spurts like a fountain. This kind of clinical, almost lecture-like delivery while threatening someone is a hallmark of how Korean dramas signal a character who is either medically trained or disturbingly calm under pressure — both qualities the show is building around Yo-han.
The doctor's phrase '상습적 자살 시도 환자' means 'habitual suicide-attempt patient' — a clinical category used in Korean psychiatric intake records. Korean hospitals are required to flag such patients for mandatory counselling follow-up, but the system is often under-resourced. The blunt delivery here reflects a familiar criticism of how mental-health crises are handled in busy urban emergency rooms. If you or someone you know is struggling, please reach out to a crisis line in your country.
The neighbour casually mentions that the priest has been regularly bringing home-cooked food to his sibling's house. Catholic priests in Korea (unlike monks) live in parish rectories embedded in residential neighbourhoods, and close personal ties with local families — including sharing meals and running errands — are a normal and expected part of parish life, making the priest's comings and goings entirely unremarkable to neighbours.
The investigator notes that the killer deliberately places bodies where a cross (십자가) is visible and makes an obscene gesture toward it — a calculated act of defiance against Christianity. This detail carries extra weight in South Korea, where Christianity (both Catholic and Protestant) has grown into a major social institution; staging a crime as a taunt toward the church signals the killer wants the widest possible symbolic audience for his contempt.
The detective drags the young officer out into the cold and sits her down at what appears to be a street stall for hot food. In Korean daily life, a warm bowl of noodles or soup from a 포장마차 (pojangmacha — a covered street-food cart or tent stall) is the standard way to take care of someone who is cold, upset, or in shock. The gesture of feeding someone says 'I'm looking after you' more plainly than words.
The office drama over a 'dongtae' (돗대) coffee stick — a colloquial term for 믹스커피 (mix coffee), the single-serve sachets of instant coffee, creamer, and sugar sold everywhere in Korea — is very real. These cheap foil packets are ubiquitous in police stations, hospitals, and offices; they even have a devoted fan base. The absurdity of a murder investigation hinging on a coffee sachet is entirely plausible as evidence because the killer, like the previous victims' belongings, leaves behind objects the victim held dear.
닭갈비 is a spicy stir-fried chicken dish — one of Korea's most popular comfort foods, especially among young people. It is typically cooked on a large flat pan at the table and eaten communally. Cooking it for someone is a very domestic, personal gesture in Korean culture, far more intimate than ordering takeout, which is why the character making it from scratch signals real emotional effort.
봉이 (Bong-i) bitterly recalls being sent on막걸리 (makgeolli) errands as a child — fetching the milky, slightly fizzy rice wine for her grandmother. Using a child as a liquor runner is technically illegal but historically common in close-knit Korean households, especially in rural or working-class settings. The line lands as an accusation: her obedience as a child led directly to harm she experienced.
The grandmother mutters that the day a certain person gets out of prison will be his 제삿날 (jesatnal) — literally his death-anniversary ritual day, meaning the day of his death. 제사 (jesa) is the formal ancestral rite performed on the anniversary of a family member's death, so calling someone's release date their 제삿날 is a very pointed Korean idiom for 'I will kill you the moment you are free.'
The priest's words at the altar are the Words of Institution from the Catholic Mass — the moment the congregation believes bread and wine become the body and blood of Christ. Korean Catholics (about 11% of the population) celebrate Mass in Korean using this same liturgical formula. The scene cuts between this sacred ritual and the investigators' urgent discovery, a deliberate contrast the show uses throughout between religious ceremony and violent crime.