Cat House

When Piper and Leo see a marriage counselor to work out their marital problems, Piper casts a spell that lets them literally see the key moments of their past. However, the spell goes awry and Phoebe and Paige are sent back in time to relive Piper's memories. Unbeknownst to Phoebe and Paige, a warlock is also caught up in Piper's spell, and uses the opportunity to try and kill The Charmed Ones' cat, their familiar, which would permanently alter their future.