On March 26, 1991, five boys set off to the mountain to go frog hunting and never come back to their family. While a documentary producer, detective and professor try to solve the mystery of the incident, one of the boys' parents is a suspect.

Little Bo-ri's family has come together – as they do every year – to commemorate her late grandfather. Bean sprouts are missing from their meal and so Bo-ri is sent off to market to fetch some. An unexpected detour takes her to places she has never seen before.