Codi meets Alice on the bus ride out of Grace. She's wearing a jogging suit and reading a gardening magazine. It turns out she knew Hallie—at least by voice. She used to call her about slugs, which is a little bit of foreshadowing in regard to Alice's character.
Alice performs a bunch of functions in the text. On the one hand, she's another example of willfully ignorant Americans who can't handle the truth of U.S.-funded violence in Nicaragua. She's also a sort of shadowy reflection of the women of Grace. Like them, she sports an odd mix of feminine objects and toughness (she's been through a pretty big loss herself), and it's no coincidence that her name, Alice, is shared by Codi's dead mother.
But Alice Kimball ultimately can't comfort Codi or care for her, because she's a stranger. Alice's inability to help shows Codi the difference between being in grace and being anywhere else.
Alice's strange familiarity to Codi allows Codi to articulate the whole story of her grief for the first time. Yet it's not a pleasant or comfortable conversation—and after Codi confesses what has happened to Hallie, the two just trail off into what is probably a super awkward silence until the end of the trip. Still, we think that despite her lameness, Alice was pretty useful to Codi. Even as they're driving away from the town, she starts Codi on the road back to Grace.