Andrew and Evie have found Mom at last. But she had to come out of hiding to get to the twins, and now the Company is on to her aliases. There's only one solution: Mom has to go underground again, and this time, she's bringing Andrew and Evie with her. The twins are used to moving to new places, so at first taking on new identities doesn't seem like that big a deal. It's kind of fun, actually. But soon Andrew and Evie realize they're not just leaving behind another town -- they're leaving behind themselves, their personalities. And there's one more thing, too... Pop.