By now the adventurers realize they are in a castle owned by Tiamat the queen of dragons. They enter an enormous room with a ceiling more than a hundred feet over their heads. There is a little old lady with five birds of different colors flying around her. Rather than killing them she offers them a choice: Fight me and die or take the contents of one of my treasure rooms (and the doors to these fly open) or do a little task for me.
The task offered is to kill a little old man who lives nearby and tends his garden and feeds his little gold birds. This old man is no old man. This old man is Bahamut.
She is, of course, no little old lady. She is Tiamat and her five little birds are her dragon mates.
The players wisely chose the middle option and took the contents of one treasure room. The castle then disappeared and Tiamat returned to her home plane.
