Time Between Dog and Wolf

Taken from drama of the same name

After his mother is brutally murdered in front of him by the Thai criminal syndicate Cheongbang, Lee Soo Hyun is adopted into NIS agent Kang Jung Ho’s family. Together with Kang Min Gi , Jung Ho’s son, Soo Hyun becomes an NIS agent. When Soo Hyun met Suh Ji Woo they were about twelve years old and has another fateful encounter with her 13 years later. Together they had promises for the future.
One day, Soo Hyun leaves for an operation dealing with the Cheongbang, only to return in failure because of the resurfacing terrible childhood memories of when he was in Thailand. The chief of NIS agents, Jeong, proposes to the distraught Soo Hyun to infiltrate the Cheongban...