The author of “The Woman in Cabin 10” and “In a Dark Dark Wood” is back with another page-turning thriller. But while readers will surely turn the pages until the end, “Zero Days” doesn’t quite ascend to the level of Ruth Ware’s previous bestsellers.

The star of the story is Jacintha “Jack” Cross. Jack is a penetration specialist, a “pen tester” who breaks into offices with the help of her hacker hubby to test the security of British companies. The novel begins with Jack on the job, flirting with her husband, Gabe, on a headset as she navigates a corporate headquarters. By page 34, and this is not a spoiler given it’s on the back of the book, Gabe is dead and Jack is the No. 1 suspect.

Ware has a knack for creating female protagonists worth rooting for, and Jack, “five foot two” and a fan of eyeliner, is no exception. It’s the plot that gets in the way. Despite chapter headings that count backward to zero (“Minus Eight Days”) and suggest something big at the end of the countdown, a majority of the book is spent entirely inside Jack’s head as she ponders and plans her next move. There’s not enough interaction with other characters to make it feel more propulsive and to heighten the sense of danger.

When she does speak, Jack sometimes sounds a little too one-note. “It’s that or rot in prison for the murder of the man I love!” she tells Gabe’s best friend as she hatches a scheme to try to uncover the killer. With Gabe gone, she still hears his voice in her head — “You’ve got this!” — and it all feels just a little too predictable.

The best scenes are near the end, when Jack finally gives herself more than a moment to grieve. She cries “great hacking sobs that seemed to be wrenched uncontrollably up from somewhere deep inside of me,” as her ordeal finally ends. Along the way, there are some fun twists and turns, and Ware fans, or fans of quickie thrillers in general, will probably finish it in a weekend. First-time samplers of the genre, however, would be better off reading something from the writer Ware has mentioned often as an influence, Agatha Christie.