For every light, there is always a shadow. Imagine if you will, all the monsters that you envision in your dreams and nightmares. Vampires, Lycans, Changelings, Ghosts, Robots. For eons, we have all but considered these beings to not exist. They have always been in the periphery of our minds, always in myth and legend.

But what if I told you that all these things were real?

In a secret world, hidden behind a careful masquerade, guarded faithfully within the tower of Tartarus, these creatures not only exist, but live together in strange harmony with one another.

Welcome to Penumbra, the Shadow of Equestria. Where the sun never shines and the moon glistens in imperishable night. My name is Adam, and I've just become its latest resident.

(This is a sequel to On Light Hooves I Tread 2: Homeward Bound. While reading it is not required, it may help to read that story and the previous one to get a grasp of what's going on. It is also a Crossover with Dungeons: The Dragoning, in a sort.)