Suspecting that Billie and Christy are the 'Ultimate Power,' Phoebe and Piper formulate a plan that will provide the answers they need to get Leo back. Meanwhile, Paige saves her new charge Mikelle from two Darklighters, and Christy traps the sisters in a dream state in order to prove to Billie that each of their 'inner-truths' are driven by selfishness.