Kalit so'z National Intelligence Service Nis

Children who live in hiding with superpowers, along with their parents who live with painful secrets of the past, face enormous dangers together.

Stuntman Cha Dal-geon gets involved in a tragic airplane crash and ends up discovering a national corruption scandal in the process. Go Hae-ri, the oldest daughter of a deceased marine, decides to work for the National Intelligence Service as a secret ops agent in order to support her mom and younger siblings, although all she wanted to do is to become a civil servant.

Han Ji-hyuk, an NIS agent gone MIA, returns after one year to join a new team as he searches for his lost past.

Kwon Dohoon is an expert sniper and a secret agent working for the National Intelligence Service. To conceal his true identity, he lives a double life as a regular trading company employee, keeping even his wife Kang Yura in the dark. Though he is occupied with his work, Dohoon cherishes his wife deeply. Meanwhile, Yura, a dedicated homemaker, harbors a secret. Their tranquil existence is thrown into turmoil when Jo Taegoo emerges, posing a threat to their carefully crafted façade.

After his mother is brutally murdered by the Triad in Thailand, Soo-hyun is adopted by NIS agent Kang Joong-ho, and he grows up with Min-ki like brothers. Min-ki and Soo-hyun both become NIS agents later on. One fateful day, Soo-hyun meets Ji-woo after last seeing her in Thailand when he was a child. They start dating. One day, Soo-hyun ruins a mission when the suppressed memories of the day his mother died surfaces in his mind. NIS Director Jung gives Soo-hyun an undercover assignment to infiltrate the Triad and Soo-hyun takes the job. Soo-hyun fakes his death and assumes a new identity to become a member of the Triad. With his fake identity and new name, he prowls the back alleys of Bangkok.