Charmed and Dangerous

Plot:

The Source breaks an age-old agreement between good and evil by stealing The Hollow, an ancient vapor which he uses to absorb Piper and Paige's powers. Meanwhile, Phoebe must allow Cole to help them, despite her having a premonition involving Cole sacrificing his life to save her from a demon, but there may be more to the premonition that Phoebe just can't see.