Sang-yeol and Mi-na are a married couple; he works as a magazine reporter, she is a well-known writer. Sang-yeol, who mostly works from home, has been having an affair with his neighbor and colleague, Da-yeong, for a while. Mi-na discovers Da-yeong's number after a chance encounter and begins to suspect the frequent calls her husband receives from it. She learns about the affair but surprisingly isn't angry. Da-yeong's husband, Hyeon-woo, is someone she had previously dated. While working, Mi-na unexpectedly meets Hyeon-woo and initiates a relationship with him, leading to a complicated web of connections.