General · EdgepediaOctober 3, 20266 min read

The King's Case Note (임금님의 사건수첩)

The King's Case Note (임금님의 사건수첩, Imgeumnimui Sagunsoocheob) is a 2017 South Korean comedy-adventure film directed by Moon Hyun-sung, in which a clever Joseon king and his new royal chronicler investigate a strange rumor and a crime that threatens the throne¹. It stars Lee Sun-kyun as King Yejong and Ahn Jae-hong as the record keeper Yi-seo, and it was released in South Korea on April 26, 2017².

Key fact	Detail
Release	April 26, 2017 (South Korea), 114 minutes, rated 12+¹
Director	Moon Hyun-sung, in his second feature after As One (2012)³
Source	Webtoon of the same name by Heo Yoon-mi, published 2012–2013 in the magazine Wink⁴
Lead cast	Lee Sun-kyun (King Yejong), Ahn Jae-hong (Yoon Yi-seo), Kim Hee-won (Nam Geon-hee)²
Korean box office	1,635,003 admissions on 1,054 screens; 12,651,193,723 won, 21st among 2017 Korean releases⁵
Worldwide gross	$11,395,729, of which $90,899 came from a limited US release⁶
Critical reception	44% on the Rotten Tomatoes Tomatometer (3 reviews)⁷

Spoilers

Plot and premise

The story is set in fifteenth-century Joseon. King Yejong, played by Lee Sun-kyun, is a monarch who prefers to investigate cases himself, gathering evidence and bringing wrongdoers to justice². A new archivist, Yi-seo (Ahn Jae-hong), is appointed to the court; he is clumsy but has a near-photographic memory, and the king recruits him as an investigative partner⁸. When a strange rumor spreads in Hanyang, the capital, the two set out to uncover its source, and their inquiry into a murder turns up clues pointing to a plot to dethrone the king and destabilize the country⁴^•⁸.

The film's marketing tagline, "King by day, detective by night," captures the buddy pairing at its center⁹. Reviewers described the dynamic as a Holmes-Watson style duo: the Los Angeles Times noted a "workable, quirky Holmes-Watson dynamic" between the glib king and his loyal but somewhat clueless savant assistant, whose photographic memory proves useful against obstacles including a giant ghost fish, ominous scarecrows, and lethal herbs¹⁰.

Cast and characters

Lee Sun-kyun as King Yejong of Joseon⁹
Ahn Jae-hong as Yoon Yi-seo, the royal record keeper⁹
Kim Hee-won as Nam Geon-hee⁹
Joo Jin-mo as Jik Je-hak; Jang Yeong-nam as Soo-bin; Gyeong Su-jin as Seon-hwa; Jung Hae-in as Heuk-woon⁹
Kim Hong-pa, Kim Eung-soo, and Jo Young-jin as the Prime Minister, First Vice-Premier, and Second Vice-Premier⁹
Park Jeong-min as the Crown prince; Kang Chan-hee as the young Yejong⁹

Production

The film is an adaptation of the webtoon Imgeumnimui Sagunsoocheob by Heo Yoon-mi, serialized in the magazine Wink from 2012 to 2013⁴. The screenplay is credited to Kang Hyeon-seong, with adaptation work by Moon Hyun-sung, Jung Ui-mok, and Jungkook Han². Filming began on May 4, 2016 and finished on September 6, 2016⁴.

Production companies were Film Company RAM, CJ ENM Corp., and The Tower Pictures, with CJ ENM handling distribution and CJ Entertainment handling international sales¹. Reported budget figures put the production at $8,540,000¹¹. The supporting cast includes Joo Jin-mo as Jik Je-hak, Jang Yeong-nam as Soo-bin, Gyeong Su-jin as Seon-hwa, and Jung Hae-in as Heuk-woon, along with Kim Hong-pa, Kim Eung-soo, and Jo Young-jin as the three senior state councilors⁹.

Director Moon Hyun-sung said he wanted to break free of fixed ideas about period drama and fill the film with cinematic devices and imagination as freely as possible¹². Korean critics placed the film in a line of Joseon-era genre hybrids, comparing its pairing to Sherlock and Watson and to the Detective K series¹³.

Box office

The film opened in South Korea on April 26, 2017 on 1,054 screens¹. In its first month it drew 720,000 filmgoers, placing fifth at the Korean box office for April 2017 behind The Fate of the Furious, Beauty and the Beast, The Prison, and The Mayor¹⁴. It finished with 1,635,003 admissions and a gross of 12,651,193,723 won, ranking 21st among all films released in Korea in 2017 with a 1.4% share of the Korean-film market⁵.

That total fell short of the film's break-even point, which a year-end trade review put at 3 million admissions¹⁵. Internationally, The Numbers records a worldwide gross of $11,395,729, almost all of it from the South Korean release, with a limited United States release beginning April 28, 2017 by CJ Entertainment earning $90,899⁶. The film also opened in Australia and New Zealand on May 26, 2017⁶.

Reception

Critical response was mixed. On Rotten Tomatoes the film holds a 44% Tomatometer from three reviews⁷. Richard Kuipers of Variety wrote that the film "begin[s] brightly with goofy slapstick, irreverent humor and a dastardly plot to overthrow the monarch" but "squanders its early success in a second half marred by pedestrian pacing and ho-hum action scenes"¹⁶. Michael Rechtshaffen of the Los Angeles Times similarly found that the adventure "seldom gets sufficiently up to speed" and that the action sequences failed to compensate for the lethargic pace, while crediting the relaxed comic chemistry between Lee and Ahn¹⁰.

Korean critics were divided on the comedy. Cine 21's six reviewers gave scores between 4 and 7 out of 10, with several praising the buddy pairing and slapstick energy while one reviewer judged that the film promised comedy but delivered only small laughs¹³^•¹⁷. Audience ratings have been warmer: JustWatch records an IMDb score of 6.4⁹, and Moviefone lists a 68% audience score¹⁸.

The film was invited to the Korean Film Festival in Australia in 2017, the Paris Korean Film Festival in 2017, and the Korean Film Festival in Hungary in 2018¹.

Availability

In the United States the film streams on Rakuten Viki with a subscription and free with ads on The Roku Channel and Tubi; it is not currently on Netflix or Amazon Prime Video in the US⁹. Netflix lists the title with Korean audio and English and Korean subtitles, though availability varies by country¹⁹.

References

Topic: Encyclopedia › Arts and culture › Screen and stage › Film and television › Films and standalone screen works › Individual films by title and year › Action and adventure films (individual works) › Action comedies › Action comedies, 2000 to 2019

Initially written Oct 3, 2026 · Reviewed: Oct 3, 2026; Oct 25, 2026 · Edited: Oct 3, 2026; Oct 25, 2026; Nov 1, 2026 · Last review: Oct 25, 2026

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