In Gillian McAllister’s thrillers, her characters are often pushed to the limit and have to make unexpected and startling choices. That is precisely the case in her latest release, CALLER UNKNOWN.

At the start of the novel, Simone thinks to herself, Your children are only ever on loan to you. This is an eerie foreshadowing of what’s to come when she and her daughter, Lucy, head to the Texas desert to spend some quality time together before Lucy heads off to college. After an uneventful first night at their cabin, Simone wakes up and notices a knot of hair that looks like Lucy’s sticking to their broken front door. Further inspection shows that the teen is not just out for a stroll. She may be missing.

"[W]e...see the extreme lengths to which a mother will go to save her child regardless of the cost. CALLER UNKNOWN definitely goes there, and McAllister has plenty of surprises to unleash before everything wraps up."

The only evidence is a call that Simone receives from an unknown number. The voice on the other line warns her not to contact the authorities and gives her information about a location where they will meet up and be prepared to do a deal. Simone notifies her husband, Damien, who pleads with her to call the police. She does not follow his advice for fear of Lucy being taken from her forever.

What could have been a standard abduction and ransom saga takes several unexpected turns in McAllister’s hands. The result is a thriller that can never be labeled as predictable. Simone follows the directions of the kidnapper, and after a perfunctory first meeting goes well, she is given a second assignment that is far more dangerous. It will involve her crossing the southern border into Mexico, which Damien is completely against.

The events in Mexico kick off a series of reckless decisions that are spearheaded by Simone’s realization that her daughter is not being kept for money or any sort of drug exchange. Lucy is being held captive by an individual involved in the drug trade, whose connection to her will remain a secret here. The primary contact Simone is dealing with is bartering with her to kill someone for him in exchange for Lucy. A life for a life.

Things do not go as planned, and there is a confrontation involving Simone, Lucy and their captor that ends tragically. Simone and Lucy are now on the run in Mexico with no vehicle or plans to get to safety. They realize that the security footage circulating throughout the news and on social media does not show them in a good light. To make matters worse, Damien goes on US television demanding that they turn themselves in.

The plot continues to amaze as Simone and Lucy find out more about each other than they ever knew before. We also see the extreme lengths to which a mother will go to save her child regardless of the cost. CALLER UNKNOWN definitely goes there, and McAllister has plenty of surprises to unleash before everything wraps up.