When worlds collide, does the dust of our past remain?

When the storylines of Undertale and Deltarune converge, and Determination is scattered into the wind; Kris, Susie and Ralsei are forced to traverse an old world forgotten to time by it's bygone residents, exploring those who are mere memories left behind of the past- gathering friends both new and old, learning things they never once considered, and perhaps, forging some new connections along the way.