After Piper's memories return, she refuses to leave the Island of Valhalla and stays with the Valkyries while the others return home. Phoebe and Paige have to deal with the warriors who followed them back without the help of the Power of Three. After the warriors start attacking innocents across San Francisco, Piper and the other Valkyries arrive to try to stop the attacks. Upon learning of Phoebe's new power, Leo urges her to use it to try and turn Piper back. With the help of the other Elders, Leo tries to discover who sent him to Valhalla.

After Piper, Phoebe, and Paige have their identities and powers stolen by three evil sisters, they have their work cut out when they have to prove to Chris they're really themselves and to vanquish the fake Charmed Ones.