A fantasy medical drama about a high-ranking reaper named Kkok Du, who is the only being to exist in the underworld. Every 99 years, the cold and cruel Kkok Du must take a break from his work in the afterlife and spend 49 days in the mortal realm – and this time he ends up inhabiting the body of the human Do Jin Woo. Whilst living as Do Jin Woo, he meets Han Gye Jeol, a doctor who possesses the mysterious ability to give orders to Kkok Du.