A whitelighter came down to talk to Leo about a warlock trying to get rid of all the whitelighters so he can get rid of the witches of the world. Becaus if he gets rid of the whitelighters the witches would be left unprotected. She tells Leo that attendance for the meetings they have are mandotory and Leo says unless a charge is in need, he tells her he had to heal Piper's finger.
She doesn't buy that it was an emergancy. Her real reason for being there was to keep an eye on them to see if they could get married or not. When the elders figure out the warlocks plan they call back all of the whitelighters except Leo and the other whitelighter. When the warlock injures a witch, Leo feels her pain and it is almost too much for him to handle so he goes up with the other whitelighter letting the other whitelighter take over.
They play by her rules and she dies so they break all the rules when leo comes back, goes up to "Elderland" and kills him up there. At the end of the episode, we find out Piper and Leo can get married now.