Quick introduction

(Let's say frisk freed all monsters from the underground already??) :3

Frisk determined as ever had defeated Asriel Dreemurr and freed the monsters from the underground and 'defeated' Chara, the humans weren't so sure about it but they got used to it soon, Frisk and her friends are now living in a house together. But a few weeks later, they met a new threat, a lost person and an old 'friend'. Will they be able to stop them in time before who knows what could happen...