How far would you go to rescue your child? A mother races against the clock—and finds herself on the wrong side of the law—in a desperate fight to save her teenage daughter in this pulse-pounding thriller from the author of Reese’s Book Club Pick and New York Times bestseller Wrong Place Wrong Time.

There is nothing that Simone won’t do for her daughter, Lucy. The two have always been close, and with Lucy about to leave home for university, they depart the UK for a vacation to Texas to spend some quality time together. But when Simone awakens on their first morning in the desert, Lucy is gone, missing from their rental cabin. In her place is a cell phone, and a voice on the other line issues a shocking ransom demand. Don’t tell the police. Come to this location. And be prepared to do a deal…

Though Simone’s husband urges her to bring in the authorities for help, she knows she can’t take any chances. The kidnappers might kill Lucy if she tells anyone. No mother would take that risk. Instead, that night, she drives to the isolated meet-up.

What she finds there changes everything. The mysterious kidnapper doesn’t want money. They want Simone to do something. The unthinkable.

A catastrophic chain of events is set in motion, with chilling consequences that extend beyond Simone and her family. What follows is a heart-pounding journey through the small towns and punishing deserts of remote Texas, in which Simone’s courage—and morality—is pushed to the brink as she discovers what it truly means to be a mother.

Unbearably tense, compassionately told, and full of well-crafted moral dilemmas, Caller Unknown proves once again why Gillian McAllister’s thrillers are “the best of the best” (Lisa Jewell).