Under cover of night, Inkie and Blinkie confront a trespasser. He sways their hearts and minds with promises of adventure and discovery, and with his help, they break open a sealed passage into the heart of the rock farm. Tracing the glowing ore veins deeper into the darkness, they plummet through a false sun into a pocket dimension whose architect is an abomination older than Equestria and a personal friend of the trespasser's companion.