The trailer begins with a shot of Papyrus pointing at an elevator, saying "Hey, guys, look, an elevator! I bet there's loads of spaghetti down there! Let's go!"
Papyrus presses a button, and the elevator opens. Papyrus says "Come on, friends! Let's go!" while gesturing towards the elevator. The Gang enters, and the elevator started going down.
Suddenly, red lights start blaring, and an alarm sounds. "WARNING..ELEVATOR LOSING POWER...PREPARE FOR IMPACT." An installed speaker says on the elevator. "Oh crap.." Says Tom, before a sudden crash. Everything gets dark.
The setting is now in a strange, creepy dark lab, with lots of computer entries on the wall. Papyrus reads one. "Hmm..'This is it... Time to do what the King has asked me to do. I will create the power to free us all. I will unleash the power of the SOUL.' Asgore? Ooh, I bet she asked to get Mettaton's autograph!'"
The camera now zooms in on a strange machine that looks like a Gaster Blaster. Knocking can be heard from it. The camera now zooms down to show Sans and Papyrus walking together underneath it. The camera then shows another room with sticky seeds all over the ground, that appears to have been there for a long time. Mew gets some on her, and exclaims "Ew! What the heck is this stuff?"
It now gets all dark, and now shows this face in red: =)
Chara now appears in the light again, and says "You will not win. You should have never came back here. Didn't you forget that I had the power of the seven Human SOULs?"
Weird, melting monsters now appear in front of The Gang. "H-e-l...p-p.." They roar out in unison. The camera now shows a silhouette of a weird melting tall figure with a smaller figure crawling out of it. Tom says "Ew! You guys are gross!" when suddenly the smaller figure creates six bones, all hitting Tom in the face.
The music now ends.