11 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.
The surgeon speaks to the unconscious patient using formal but almost fatherly language, telling him not to feel wronged because he is still alive. In Korean hospitals, especially in older or traditional settings, doctors sometimes address patients directly even during procedures — it reflects a belief that awareness or spirit persists even under anesthesia.
Ba-reum reads the label fragment as the English word for intercourse before realising it is an abbreviation. This kind of embarrassing misread is played for a brief dark-comedy beat — Korean procedural dramas often use the awkwardness of English abbreviations to highlight how clinical detachment can hide behind ordinary-looking notation.
'Subject Experiment' — the notation system Han Seo-jun borrowed from laboratory animal science. In Korean university research labs, ear-punching (이어 펀치) is a standard way to permanently number individual mice in a study group. The killer has adapted this practice to human victims, piercing a finger instead of an ear.
헤드헌터 literally means 'headhunter,' a word Koreans also know from the corporate world of executive recruiting. The press gave Han Seo-jun this nickname because he decapitated victims after killing them. Korean media frequently coins punchy English-loanword nicknames for notorious criminals, similar to how American tabloids name serial killers.
제사 (jesa) is a Confucian death-anniversary ceremony held at home, usually late at night, where family members set out food, pour rice wine, and bow to honour a deceased ancestor. Knowing a suspect's mother's jesa date lets the detectives predict he might visit the neighbourhood — attending 제사 is considered a filial duty that even estranged relatives rarely skip.
숯불갈비 (sutbul galbi) means beef or pork ribs grilled over real charcoal, not a gas flame. It is a celebratory comfort food in Korea — the kind of meal someone suggests when they want to lift a mood or mark an occasion. Proposing it here signals an attempt to offer warmth after a heavy emotional blow.
비서실장 (biseo-silchang) is the head of the Presidential Secretariat, roughly equivalent to a White House Chief of Staff. In Korean political culture this person is seen as the president's most powerful gatekeeper — someone whose word carries enormous weight even though, as he points out, he technically cannot exercise the president's constitutional pardon power himself.
메스 is the Korean word for a surgical scalpel, borrowed from the Dutch 'mes.' Choi's point is sharp: a detective who wanted to kill would use his service pistol, not a scalpel — a tool that belongs in an operating theatre. The choice of weapon is the first forensic clue that the real killer has medical or surgical knowledge.
Korean correctional facilities (교도소) house inmates in large shared cells, and a rough internal social hierarchy forms quickly. Standing up for a weaker inmate, as the character does here at personal cost, is both dangerous and considered honourable — it echoes the broader Korean value of 의리 (uiri), loyalty or brotherhood, which carries weight even behind bars.
Ba-reum realises that a childhood memory he has been treating as his own actually belongs to the serial killer whose frontal lobe was transplanted into his skull. The drama draws on a folk-science idea sometimes called 'cellular memory' — the belief that transplanted tissue can carry personality or recollections from the donor. Mainstream neuroscience does not support this, but it is a well-worn device in Korean and international thriller fiction.
The phrase '전문가의 솜씨' means 'the handiwork of a professional.' Korean criminal investigators use the term to describe a scene that shows deliberate control — no panic, no unnecessary mess, an undisturbed perimeter. Recognising this detail flips the entire case: whoever killed at this scene was not an enraged amateur but someone trained to work calmly under pressure.