In-the-know New Yorkers crawl over each other to apply for membership to this community that prides itself on mentorship and empowerment. Among the hopefuls is Katie Bradley, who's just returned from the Midwest after a stint of book research blew up in her face. Luckily, Katie has an in, thanks to her sister Hana, an original Herder and the best friend of Eleanor Walsh, its charismatic founder.As head of PR, Hana is working around the clock in preparation for a huge announcement from Eleanor—one that would change the trajectory of The Herd forever.Then, on the night of the glitzy Herd news conference, Eleanor vanishes without a trace. Everybody has a theory about what made Eleanor run, but when the police suggest foul play, everyone is a suspect.

    On track for a much-needed promotion, she’s developed a system for identifying Russian agents, seemingly normal people living in plain sight.After accessing the computer of a potential Russian operative, Vivian stumbles on a secret dossier of deep-cover agents within America’s borders. A few clicks later, everything that matters to her—her job, her husband, even her four children—are threatened.Vivian has vowed to defend her country against all enemies, foreign and domestic. But now she’s facing impossible choices. Torn between loyalty and betrayal, allegiance and treason, love and suspicion, who can she trust?