Bereaved mothers seek solace in vigilantism.Five years ago, Matt and Camille Gardener's 15-year-old daughter, Emily, attended a frat party at nearby Brayburn College in upstate New York. There, 17-year-old Harris Blanchard plied Emily with booze, led her into the woods, raped her, and left her to fend for herself in the bitter January cold. Emily was suffering from exposure by the time she was found, and she died three days later. Harris' trial ended in acquittal, and Matt and Camille split. Matt made a fresh start in Colorado, but Camille still lives in the home she once shared with her family, mired in anger and grief. After Camille causes a scene at an awards banquet honoring Harris, who is now a Brayburn senior, she receives an invitation to join a Facebook group for mothers "robbed of their children by the actions of others." Her interactions there trigger another invitation-this one to a secret, anonymous dark web collective comprising mourning mothers with no desire to move on. Initially, Camille assumes the forum is just a safe space to express violent revenge fantasies, and she even posts one of her own. Then she gets a private message from the site's administrator: "Did you mean it?" Escalating stakes and a tight, twisty plot fuel this timely domestic thriller, which unfolds through a visceral first-person-present narration. Camille's pain and fury are so palpable they're contagious, and while the too-neat and somewhat rushed conclusion undermines the story's impact, Gaylin delivers a thought-provoking page-turner that grips and gratifies.An all-too-plausible tale of Highsmith-ian vengeance.