How do inmates in a correctional facility satisfy their sexual desires? A full-fledged confined-space erotic story depicting the precarious prison life of prison guards and inmates involved in sex penpals begins!

Jeong-ho fights with Ye-rin. He happened to meet Eun-jeong, the wife of a senior who passed away. He tried to win Eun-jeong's heart, who was once his first love, but she has no intentions to date another man because of her husband. Instead, Ji-hye who lives with Eun-jeong falls in love with Jeong-ho. Ji-hye is trying to match loner Eun-jeong with the junior of his husband, Joon-hyeok, but is uncomfortable. Will Jeong-ho be able to love Eun-jeong?