Fujieda Baian is admired during the day as a skilled acupuncturist. However, his nighttime persona is that of a highly skilled assassin. For money, he eliminates those whose existence is considered harmful, quietly disposing of them. One night, Baian is mistaken for another doctor by the young swordsman Kosugi Jūgorō and is attacked. He manages to avoid harm, but the doctor Kosugi originally intended to target is connected to the assassination target assigned by Baian’s boss, Hanzaemon Otowa. Baian and his companion Hikojiro begin investigating their target, Chōbei Izuyaya, the owner of a candle shop...