All his life, Victor Brom has dreamed of a mysterious town with old houses and deserted streets covered in a misty haze. After the mysterious death of his mother, Brom discovers her secret diary, from which he learns that the Forgotten City really exists: it is hidden from the rest of the world among impenetrable forests under an eternal shroud of fog. But why does no one know about this place? Who inhabits it? And what secret does Victor Brom's own past hold? To answer these questions, he travels to the Forgotten City, where he encounters the mysterious Guardians - and the danger that the fog conceals. Soon Brom realizes: there are wonderful people living in this city, but some of them are real creatures.