-려고 하다
Attach -려고 하다 to a verb stem to show intention or purpose, like 'intend to' or 'try to.' It is very useful for talking about plans that may be interrupted or followed by an unexpected result. In the story, 준호 says: "계산하려고 돌아가 보니 상점은 이미 문을 닫았다." You can reuse this pattern in everyday Korean: "저는 버스를 타려고 일찍 나왔어요." This means 'I came out early because I was going to take the bus.'
계산하려고 돌아가 보니 상점은 이미 문을 닫았다.
When he went back to pay, the shop had already closed.
