The secrets they left behind : a mystery / Lissa Marie Redmond.

Enhanced descriptions from Syndetics:

Three missing girls, no leads, a vault of dark secrets, and a case that's getting chillier by the minute, set the stage for this nail-biting procedural from former cold case homicide detective and acclaimed author Lissa Marie Redmond.

Three college freshmen go missing from their rural hometown of Kelly's Falls while on Christmas break. Their cell phones, coats, and purses are left behind, but the girls have disappeared without a trace. As the days turn into weeks and the investigation grows cold, twenty-three year old Buffalo police officer Shea O'Connor is called on to dig up leads undercover.

Still bearing the emotional and physical scars of a previous case, O'Connor infiltrates as eighteen-year-old Shea Anderson, a college freshman and the "niece" of the town's police chief. As she begins to immerse herself in the missing girls' world, befriending their friends and family, and doing whatever it takes to maintain her cover, O'Connor realizes the track is far colder than she initially thought. But whoever was behind the girls' disappearance was only warming up, and they have set their crosshairs directly on her.

The heat is on for O'Connor as she closes in on the shocking truth about what really happened the night the girls vanished.

Reviews provided by Syndetics

Publishers Weekly Review

Buffalo (N.Y.) PD patrol officer Shea O'Connor, the 23-year-old narrator of this engrossing mystery from Redmond (The Murder Book), has engaged in an undercover assignment for FBI agent Bill Walters that left her with emotional and physical scars. Bill now coerces her to work undercover in Kelly's Falls, a town south of Buffalo, where three girls, all college freshmen, disappeared during Christmas break, leaving behind their purses, cellphones, and jackets. She poses as Shea Anderson, a college student who has supposedly come to live with her uncle, the police chief of Kelly's Falls, after her parents died in a car accident. Shea immerses herself in the lives of the victims' families and friends, but danger looms when her real and undercover identities begin to overlap. Her growing attraction to the brother of one of the missing girls raises the emotional stakes. Redmond, a former cold case homicide detective, skillfully doles out the plot twists. Fans of small-town police procedurals will be satisfied. Agent: Bob Mecoy, Creative Book Services. (Apr.)

Kirkus Book Review

A Buffalo cop who's gone undercover for the FBI finds herself in a world of hurt.Shea O'Connor is 23 but looks 18. That's why the FBI used her to pose as a high school student to catch a serial killer, a case that left her scarred both physically and emotionally. The case is still under a gag order and Shea is back on boring patrol duty when FBI Agent Bill Walters asks her to work another case for him. Three freshmen college friends all went missing the same night in the little town of Kelly's Falls, New York. Against her better judgment, Shea accepts and is set up as Shea Anderson, a transfer to Harris Community College whose parents were killed in a car accident and whose uncle is the town police chief, Roy Bishop. Since her fake uncle is youngish, unmarried, and unhappy she's interfering in his case, she's put up in a boardinghouse. Emma Lansing and Olivia Stansfield, two of the missing girls, came from a nice area; the wilder Skyler Santana lived in a trailer park with her alcoholic mother while her drug-dealing boyfriend, Joe Styles, worked on a GED at Harris. Shea immediately becomes friends with the missing girls' buds, Kayla, Jenna, and Maddie. She fends off passes from Joe while recognizing his bad-boy appeal to young girls. Shea has no trouble fitting in and easily gains her new friends' confidence. But she still suspects that they're hiding information that could be the key to breaking the case. Even worse, she and Nick Stansfield, the brother who refuses to go back to RIT until Olivia's found, fall for each other, and she hates herself for deceiving him. Redmond (A Means to an End, 2019, etc.) shows tensions mounting as Shea struggles for answers along with a town united in its resolve to find the missing girls.A page-turner whose puzzling mystery and psychological drama are rooted in plausible descriptions of teenage angst. Copyright Kirkus Reviews, used with permission.