As illegal firearms flood into a gun-free South Korea, a resolute cop and a cunning arms broker find themselves at odds in a tense showdown.

A psychopath's ruthless serial murders have left the entire nation gripped with fear and chaos. A honest and justice-seeking rookie police officer and a veteran detective with tragic past, face against the killer. After the encounter with the psychopath, their lives totally change.

Se-ha who is physically handicapped and Dong-gu who is mentally handicapped are not their own brothers. But while living 20 years together, the two became indispensable to each other. One day, the mother of Dong-gu suddenly visits him and acts as his guardian.

Moon Ha-won is an AI programmer and he is the founder of AH Company. He is a consistent person with a good heart. Meanwhile, Han Seo-woo works as a classical music recording engineer. Her life is unstable without a family or house, but she is a positive person.

The stories of ambitious career women working at the top of the best portal sites in the IT industry. Paved with wins and losses, their road to success takes a new turn when love comes along the way.

Kim Ji-young, an ordinary woman in her 30s, suddenly shows signs of being inhabited by other women from her life, past and present.