"A portal suddenly opens in front of you, what do you do?"

Party all walks through portals into hueco mundo unknowningly, suddenly a party member burst into flames, then another starts digging and they fall into another layer of hueco mundo, they stealth their way past some menos before facing some unawakened arrancars and running away and fighting a centaur hollow, blasting a hole in reality to be someone elses problem as they ran away from all their problems and got home finding they had a mysterious vial on them.