University students Eun Yeong-Ro and Lim Soo-ho go on a blind date, and Yeong-ro quickly falls in love. However, Soo-ho hides a dark secret about why he is visiting Yeong-Ro's university.

After sustaining several bullet wounds, Soo-ho breaks into the Women's University Dormitory at night and runs into Yeong-ro. Yeong-ro and her roommates try to discover who Soo-ho really is.

Yeong-ro tries to take care of Soo-ho in her attic without being noticed by the faculty staff and the National Security Agency whilst also preparing for the university's annual open house.

Soo-ho secretly leaves Yeong-ro's dorm in order to restart his important mission. The dorm's phone operator and housemother begin to suspect that Yeong-ro is hiding something from them.

Soo-ho is forced to hold the students and staff of the Women's University hostage, causing Yeong-ro to doubt her feelings and the person she had so suddenly falling in love with.

Soo-ho continues to hold the students hostage, despite Yeong-ro's protesting. A doctor is sent into the dorm in order to help the wounded as the ANSP start to close the net around them.