The Fourth Sister

When Piper, Prue and Phoebe are befriended by a troubled young witch, she hopes they'll take her under their wings and become her mentors. However, things change when she gets lured by a sorceress into pursuing dark magic and the sisters try to break the sorceress' spell over the girl. Meanwhile, as Piper and Phoebe vie for Leo's attention, Prue tries to find time to spend with Andy.