Kim Jun thought running away to the military for two years would erase the shame of kissing his academic rival, Cha Siwon. But returning to college drags them right back into each other's orbit through shared classes and identical phones. When an accidental mix-up forces Siwon to answer a strange call on Jun's phone, explicit moans on the receiver instantly shatter Jun's innocent facade. Exposed and cornered, Jun finds his academic rivalry devolving into an addictively dangerous game of control and submission.