When an unknown toxic gas strikes Seoul in an unprecedented act of terror, Yong-nam has just met Eui-ju from college by chance at his mother’s birthday banquet. The city falls under sudden noxious gas attack and together, they must escape the panic-stricken city.

A mother lives quietly with her twenty-eight-year-old son, Do-joon, providing herbs and acupuncture to neighbors. One day, a girl is brutally murdered, and Do-joon is charged with the killing. Now, it’s his mother’s call whether to prove him innocent or to leave him imprisoned.