Beneath the surface of the modern world lies a secret so ancient and terrifying that the only proof of its existence is the silence of those who have seen it. Those who do know the truth live in one of two ways; in absolute fear, or in absolute devotion to keeping it hidden. When a disturbing incident in Russia sets something unstoppable in motion, the shadows of mysterious beings that have kept this secret buried for centuries begin to close in on Seoul. And when they do, those bound by the oldest of oaths are called to act. Because if they fail, something the world has forgotten how to fear will be unleashed again.