When Alison was stuck in Mirrorland, all she wanted was to be alive again. Now she's gotten her revenge by inhabiting Piper's body and trapping her behind the mirror. But pretending to be Piper is more difficult than she imagined it would be.On top of that, the borders between Mirrorland and the real world are crumbling. Danger abounds, demons appear in high school, and if wasn't for the help of a new mysterious guy, Alison might not have escaped. But there's more to this guy than meets the eye, and she's determined to find out what, especially since it might be related to her own supernatural problems.Meanwhile, Piper tries to convince the Horseman of Death to help her return to her own world, but he's got his own hidden agenda, which may cause more serious risks. Can Piper find a way to restore the balance before both worlds collide?