Lee Mu-saeng, left, and Kang Dong-won attend a press conference for the upcoming thriller "The Plot" in a cinema in Seoul, April 29. Yonhap

Plotting a killing to appear as an accident, as depicted in the upcoming thriller "The Plot," proved more challenging than anticipated, the director said Monday.

"When devising a murder scheme in the movie, the most intriguing aspect was figuring out how to eliminate someone without resorting to lethal weapons," director Lee Yo-sub said at a press conference for the movie on Monday.

"I contemplated numerous methods in my mind, and I must say, it was quite challenging."

Adapted from the 2009 Hong Kong movie "Accident," "The Plot" centers around Young-il (played by Kang Dong-won), who leads a contract killing group that meticulously designs murders to appear as perfect accidental deaths.

Things take an unexpected turn as Young-il and his team become embroiled in a new, perilous mission to kill a well-known and influential figure.

"Each character has a hidden side and undergoes changes as the story unfolds. It will be interesting for audiences to discover that in the film," the director said.

Actor Kang of "Dr. Cheon and Lost Talisman" (2023) and "Broker" (2022) said Young-il was "the coldest and driest" character among those he has played so far.

"Following the death of a longtime colleague, Young-il becomes suspicious of everything that happens thereafter," the actor said. "He is a lonely figure who trusts no one and believes he could also be the target of a plot."

In the film, Young-il undergoes significant changes as he believes he himself has become a target of such schemes.

The director emphasized his focus on portraying the "unique" tension in the film, derived from the suggestion of sinister conspiracies hidden behind ordinary occurrences, particularly through the use of sound.

"The Plot" marks the second feature movie directed by the filmmaker, following his debut thriller "The Queen of Crime" (2016), which revolves around a mother investigating the suspicious circumstances surrounding her son's water bill bomb.

The film also stars Jung Eun-chae, Lee Mu-saeng and Lee Mi-sook, portraying Young-il's client, a mysterious insurance company employee contacting the client and his seasoned colleague, respectively.

It is set for release on May 29. (Yonhap)