Say Yes (2001)

Cast
Park Joong-Hoon as Em
Chu Sang Mi as Yun-hie
Kim Ju-Hyeok as Jeong-hyun

Trailer

Synopsis
Young married couple Yoon-hee and Jung-hyun go on a road trip, and along the way they pick up a lone drifter, Em. Em turns out to be a violent and sadistic psychopath who terrorises the couple at every turn. After capturing Jung-hyun, Em gives him a choice: submit to torture or allow Em to kill Yoon-hee.