Ploy
พลอย (original)
A husband and wife are locked inside a single hotel room with a stranger named Ploy. Subtle suspicions build up to jealousy as the young woman triggers devastating consequences for the couple.
Starring Lalita Panyopas, Pornwut Sarasin, Apinya Sakuljaroensuk, Ananda Everingham, Porntip Papanai, Thongchai Wongthongdee, Sunisa Buranabut, Phimchaiphut Khongkha, Thaksakorn Pradapphongsa, Natthapong Iamsangtham
Watch "Ploy" on Kanopy released in 2007. It's a drama and action & adventure movie, and has a rating of 6.7 out of 10 from Imdb which is usually fine for this kind of movie.