1937, Gyeongseong, Joseon.

There existed a heretical figure known as the 'Shamaness in Black', whose existence was concealed by the Government-General of Joseon. A penny dreadful horror novelist from Japan, Iwaya Kyousui, pushes his way into accompanying her in order to conduct research for a novel he's writing.

A tactless novelist and a heretical shamaness form an unlikely partnership, unfolding a Korean occult action story.