Son's First Love.

Sang-woo who had his stepmother as his first love tells his brother everything. However, his younger brother Bong-soo confesses that he knew Sang-woo slept with their stepmother. The three people who know they've had sex with each other get together and tell each other to be careful not to get caught by their father. Sang-woo sends his younger brother Beacon to a massage room to spend time alone with his stepmother Soo-ji. Bong-soo, who arrived at the massage room, tells So-ra, his girlfriend who works at a convenience store not to work again. Sang-woo takes Bong-soo back home. They run away together after hearing that their father caught them running out of the house screaming.