At the depths of ever interwinding tunnels, a pregnant rat stumbles upon a large gemstone. Within its glass surface rages a whirlpool of green light, beckoning the rat with its glow. She draws closer, urged on by a strange power, to find a puddle of green goop leaking from cracks in the stone.

hesitantly, the rat gnaws at the liquid, and reels back from a sudden power surging into its small body. It sprawls, claws scratching at the rough stone floor in an attempt to leave this strange room, to flee from the gem, to no avail. The power pushes from her insides, forcing the rat to twist and expand with each step as she grows beyond a wolf, beyond a bear, ever beyond as she keeps running.

Prematurely, the giant rat gives birth, but it's young are alive. Creatures, bearing eerie resemblance to rats. However, not quite…