"You are the first human to remain sane after smelling my scent for two hundred years." Beom Tae-hoon is the CEO of the architecture firm 'In' and a celebrity in the architecture world. He appears perfect, but he hides a fatal secret: he is a 'Sang-gun' (mountain spirit), a tiger who has lived for 200 years. When his rutting cycle begins and he is on the verge of losing his reason, his straight-forward secretary, Lee Seol, who has a crush on him, enters his office trembling. "Rather than watching you marry someone else, I'd rather be devoured by you." That single sentence snaps the string of his self-control. On a night of pouring rain, the office door locks, and the tiger's intense and long feast begins.