The family which operates a medicine wholesale business undergoes an upheaval which leads to the splitting into two factions Ganso and Honke. One day, Kiichirou, the eldest son of the Honke faction, poisons the Ganso household head Nagahiko and goes missing. Two years later, Kiichirou's younger sister Hatsue asks Kindaichi (Yamashita) to look for her brother. (mydramalist.com)