How far would you be willing to go to save the ones you love? With his grandfather bordering life and death, Taesun takes on multiple jobs in order to pay a seemingly endless stack of hospital bills. On one of his odd jobs, he ascends the great mountain Geumryang, unknowingly the home of an eponymous serpentine spirit. When Taesun encounters the divine being, he too is on the brink of death, desperate for water in his slithering form. Taesun offers him a sip of water and saves the sacred snake from certain death. Later that night, a cold-blooded body embraces Taesun and offers him an exchange: bear the ancient being’s seed, and his grandfather will live. But is all really as it seems? After all, can one ever truly trust the forked tongue of a serpent…?