Piper is surprised when Leo returns to town, looking for her help in protecting an innocent woman from being stalked by demon stalker. It is only after Piper casts a spell on Leo that she discovers that he is a whitelighter assigned to protect the Charmed Ones. As a result of the spell, Prue and Phoebe's powers get switched as well and as a result, their powers are weak when they go up against the demon, but ultimately are able to save the day.