Your name is Asriel Dreemurr, and you are a crybaby and a bully-magnet. Desperate to prove your classmates wrong when they call you a wimp who can't do anything without crying to mommy, you accept a dare to climb to the top of Mt. Ebott.

You fall.

Now, trapped underground, you have no choice but to trust the strange monster children, Frisk and Chara, who have found you and promised to help you find your way back to the surface.