Question: What is 2015 South Korean slasher-thriller film directed by Hong Won-chan and starring Go Ah-sung and Park Sung-woong, that starred a a South Korean actress who began her career as a child actress?

Context articles: Park Min-ha (actress)
Go Ah-sung
Thread of Lies
Radiant Office
The Host (2006 film)
Hidden Identity (TV series)
Master of Study
For the Emperor
Heard It Through the Grapevine (TV series)
Office (2015 South Korean film)

Park Min-ha (born July 2, 2007) is a South Korean actress.
 Park began her career as a child actress in 2011, and has appeared in such productions as the South Korean disaster film "Flu" (2013), the Korean drama television series "King of Ambition" (2013), and the music video for K.Will's song "Love Blossom" (2013).
 Her father is SBS anchorman Park Chan-min.
Go Ah-sung (born 10 August 1992) is a South Korean actress.
 She began her career as a child actress, notably in 2006 top-grossing blockbuster "The Host".
 This was followed by major roles in "Snowpiercer" (2013), "Thread of Lies" (2014) and "Office" (2015), as well as the TV dramas "Master of Study" (2010) and "Heard It Through the Grapevine" (2015).
Thread of Lies (; lit.
 Elegant Lies) is a 2014 South Korean film based on the 2009 bestselling novel "Elegant Lies" by Kim Ryeo-ryeong.
 Directed by Lee Han, it starred Kim Hee-ae (in her first film in 21 years), Go Ah-sung, Kim Hyang-gi and Kim Yoo-jung.
Radiant Office (Hangul: 자체발광 오피스 ; RR: "Jachebalgwang Opiseu "; lit.
 "Self-Dazzling Office" ) is a 2017 South Korean television series starring Go Ah-sung and Ha Seok-jin.
 The series is written by a rookie screenwriter who won the 2016 MBC TV Drama Screenplay Competition in Miniseries category.
 It aired on MBC from March 15 to May 4, 2017 on Wednesdays and Thursdays at 22:00 (KST) for 16 episodes.
The Host (; lit.
 "Monster") is a 2006 South Korean monster film directed by Bong Joon-ho and starring Song Kang-ho, Byun Hee-bong, Park Hae-il, Bae Doona and Go Ah-sung.
Hidden Identity () is a 2015 South Korean television series starring Kim Bum, Park Sung-woong, Yoon So-yi and Lee Won-jong.
 It aired on tvN from June 16 to August 4, 2015 on Mondays and Tuesdays at 23:00 for 16 episodes.
Master of Study (; lit.
 "God of Study", "Lord of Study") is a South Korean television series that aired on KBS2 from January 4 to February 23, 2010 on Mondays and Tuesdays at 21:55 for 16 episodes.
 It starred Kim Su-ro, Bae Doona, Oh Yoon-ah, Yoo Seung-ho, Go Ah-sung, Lee Hyun-woo, Park Ji-yeon,
For the Emperor () is a 2014 South Korean action noir film directed by Park Sang-jun, starring Lee Min-ki and Park Sung-woong.
Heard It Through the Grapevine () is a 2015 South Korean television series starring Yoo Jun-sang, Yoo Ho-jeong, Go Ah-sung, and Lee Joon.
 It aired on SBS from February 23 to June 2, 2015 on Mondays and Tuesdays at 21:55 for 30 episodes.
Office (오피스 ) is 2015 South Korean slasher-thriller film directed by Hong Won-chan and starring Go Ah-sung and Park Sung-woong.
 It is about a detective trying to figure out why a mild-mannered man has killed his family and is targeting his co-workers.
 The film premiered at the Midnight Screenings section of the 2015 Cannes Film Festival.