Determination (A Frans Fanfiction)

What will happen after Chara resets and begins a pacifist run for no apparent reason? Sans is cautious, for good reason, because there is a more sinister plan afoot. Frisk is being held captive inside her own mind, and Chara plans to destroy the pacifist run from within. Can Frisk take back her mind and save the underground from the evil within it?
Cover credit to SkullsNBones! c: