Charmed (1998) : 1x20

After Piper leaves on a business trip, it doesn't take long for some friction to appear between Prue and Phoebe. However, they set their differences aside when they run into a ghost of a serial killer who's looking for a revenge against people who sentenced him with a death penalty. Meanwhile, the many unsolved crime cases are finally starting to catch up with Andy when people from Internal Affairs take an interest in them.