After getting pulled into an unexpected incident, the gumiho Lee Yeon (Lee Dong-wook) is thrust back in time to 1938. There, he crosses paths again with Ryu Hong-ju (Kim So-yeon)—a former west mountain guardian spirit who now runs a high-end restaurant—and his estranged younger brother, Lee Rang (Kim Bum). Lee Yeon faces a hostile reunion with his former friend and ex-mountain spirit Cheon Mu-yeong (Ryu Kyung-soo) while navigating an era of occupation and turmoil, desperately searching for a way back to the modern era.