Red Bikini.

A couples' trip to Pattaya turns into hell when each others' secrets come out into the open! Soo-jeong and Tae-hyeon decide to go abroad with Sang-jin and Ji-hyeon to celebrate Ji-hyeon's birthday. However, Ji-hyeon can't make it last minute and the three set off. However the local tour guide tricks them into losing everything they've got. Then they meet Lizzie, who Sang-jin falls for right away. They cross the line and Soo-jeong who secretly had a crush on Sang-jin, films them quietly. She then threatens Sang-jin to tell Ji-hyeon with the video of their affair and demands he takes her in. Tae-hyeon finds out about everything and the dreamy vacation turns into hell...