Seven years of silence, a family's truth unveils

Late at night, a Korean man, Chi-hoon, visits his older sister’s house which is located in a residential area in the United States. He knocks on the door and it is Mun-seok, the husband of Chi-hoon’s sister, who welcomes Chi-hoon. The two start drinking. While having conversation, the truth that will determine the fate of their family is revealed. What on earth happened to this family?