After Mylie, a mermaid turned human makes a deal with a sea-hag, she turns to Piper, Phoebe, and Paige after their pact turns out bad. As a result of the sisters' helping her out, Phoebe gets turned into a mermaid. Meanwhile, as this is playing out, Phoebe's divorce of Cole gets put on hold when he returns, begging her to take him back. Cole then decides to help Daryl out in an attempt to get back on Phoebe's good side. As Paige struggles to find a balance between her work as a Charmed One and a Social Worker, Piper struggles to face her fears of a water demon.