Make Them Pay by Allison Brennan is the 12th book in the Lucy Kincaid series (available March 7, 2017).
Lucy Kincaid and Sean Rogan are finally tying the knot. Two weeks before their wedding, a surprise visitor shows up at their door: Eden, Sean’s estranged sister from Europe. She claims she’s in town for the wedding and wants to mend fences. Lucy invites Eden to stay with them—after all, family is family—but her boss, SSA Noah Armstrong, knows far more about Eden’s sketchy past than he’s let on.
While Lucy is focused on her investigation tracking down dozens of children sold through illegal adoptions, Noah begins a quiet investigation of Eden and her elusive twin, Liam. He’s certain that, since they’re both thieves, they're here for a job or a heist. But they are up to something far more sinister than even Noah can imagine.