A few weeks after leaving the Underground, Frisk decides to look around the forest near her house. She walks right through and finds a huge castle. That night, she takes Sans, Papyrus, Undyne, Alphys, Mettaton, Napstablook and Monster Kid to explore the place. Little do they know, it's not uninhabited. In fact, hundreds are there. And out of these hundreds, the first they meet were a few boys who are famous for pranking.
