In 1692, in Salem, Massachusetts, the evil warlock Matthew Tate is trapped in a locket by Melinda Warren before she is being burnt at stake. In the present days, the also evil Rex Buckland and Hannah Webster, give the locket to Prue as a piece to be cataloged, and Prue accidentally releases Matthew, the real intention of the wicked double. Matthew steals Prue's power and while chasing Piper and Phoebe to get their powers, the trio resurrects Melinda to help them to curse the powerful Matthew and imprison him again.
"The Witch Is Back" is another good episode of "Charmed", where the evilness and malice of Rex and Hannah are disclosed a little bit more, but not their master. The romance between Piper and Leo seems to have finally started.