Hyeon-dae (Lee Sang-won) and Min-joo have maintained a secret, long-standing sexual partnership under the mutual understanding that their affair would cease once either of them got married. However, when marriage actually enters the picture, neither can suppress their physical desires. Continuing their secretive sexual relationship beyond the marriage boundary, Hyeon-dae spirals into self-destruction, while Min-joo refuses to relinquish her attachment, creating an increasingly toxic cycle of betrayal involving their respective partners.