In a desperate move to save the life of her parallel self, high school science genius Audie Masters managed to bend the laws of physics. But now she's trapped in the wrong universe, with no sign that her scheme to save her alternate self, the famous teenage explorer and adventurer Halli Markham, actually worked. Until she can sort out the physics of what went wrong, Audie has to pretend to be Halli--and fool everyone from Halli's parents to the guy who's in love with her. And meanwhile there's her own life Audie would like to reclaim, including Daniel, the only one who knows the truth about who she really is. Is Halli still alive? If so, where is she? And can Audie ever find her way back to her own universe, her own family--her own life?