Book excerpt: At Foxham Prep, a posh private school for Washington, D.C.'s elite, a rumor gains momentum as it collects followers on social media, pulling three girls into its path--Bryn, who wants to erase all memories of the mistake she made last summer; cheer captain Cora, who desperately wants to believe in her boyfriend's faithfulness; and shy Georgie, newly hot after a summer at fat camp and ready to reinvent herself--but who can stop a dangerous rumor once it takes on a life of its own?