Star drags Marco into the future because she is curious about what their future holds. Both of them are greeted by their future selves, but Marco has a bad feeling when they're stuck in the future.

Earth and Mewni have now merged into one; all because of a rebel mewman princess and human safe-kid's love for one another (and magic, of course)! Now that they live in...well, sort of a brand new world, Star and Marco have many new adventures in store! However, one question remains. Are they ready for what is coming their way?