A former arm-wrestling champion raised in the U.S. returns to South Korea for a tournament that could return him to glory, but he finds his life complicated by the appearance of the biological family he never knew.

An aspiring singer Sun-deok is visited by her mother, whom she hasn’t spoken to in years. The abrupt encounter leads to the news of her younger sister Yuri, who had vanished with their savings. The mother-daughter team is now hunting for the missing girl and their money, poking around in Itaewon, the international hub of Seoul. Little do they know that soon they will be faced with Yuri’s unlikely secrets.

Wooju brings a corpse to his lover Jisu's place. Meanwhile, Giwan has a nightmare that he's floating in space. He searches for articles about rocket launches every day.