'Trap' is a cross between a romance and thriller that tells the story about the love, temptation, and betrayal that occurs among university students in their twenties.
The story focuses on Yun Doo, a studious, normal girl. An old partner won't stop bothering her through messages, so she makes up that she has a boyfriend and posts a random photo of a guy. That picture turns out to be from Hyun Ho, one of the most popular and rebellious of the school. It's a school drama, with several romances in sight.