Heroes Next Door S01 E02 Butane Gas, My Ass

"Heroes aren’t born—sometimes, they live next door"

Choi Kang is suspected of being a spy after a clash with a foreigner of unknown nationality. While tracking the foreigner's secrets with Kwak Byung-nam and Lee Yong-hee, he discovers an unexpected clue. This clue connects to Choi Kang's past.