” ‘Are you going to catch them?’ she said.

“I made the promise without hesitation or even a hint of uncertainty. ‘Yes, I told Alex. I’m going to catch those men so they can’t do this to anyone else.’

“That night, as I drove home to tuck my own kids in bed, my mind kept going back to that moment, and to the single thought that would stick with me for the months to come Don’t let her down.”

Chapter one of this riveting nonfiction book by veteran South Portland police detective Steve Webster ends with these words. The year is 1998, and Webster has just interviewed two girls ages 7 and 10. Earlier that day, four home invaders bound the girls with a video-game cord and threatened them with death if they didn’t tell where their family stashed its money.

There was no money in the house and, miraculously, the girls escaped physical injury.

Webster, a Portland native who began his career with the South Portland PD in 1987, has seen a lot of crime and cruelty during his 24-year career. He’s been a patrolman, a detective and an officer in the Maine Drug Enforcement Agency.

But, as he explains in “One Promise Kept,” the book he co-authored with Portland Press Herald court reporter Trevor Maxwell, every police officer has a case that haunts him start to finish. The heartless treatment of 7-year-old Alex Tran and her cousin by four criminals haunted Webster, and it’s the main subject of this page-turner.

In fact, Webster’s book deals with a lot more than solving a single crime. Alternating with chapters focused on the Tran case are other true stories that may shock readers who prefer to think of Maine as a peaceful place where life is what it should be.

Among incidents detailed by Webster is a criminal’s attempt to run over a plainclothes policeman with a speeding car. Death is avoided when the athletic cop jumps into the air at the last possible second, bouncing off the car’s windshield with only a broken foot to show for what would otherwise have been certain death.

This is a book with lots of action, but never the simplified television version of police work. Webster has empathy. He learns early on that poverty and ignorance are breeding grounds for crime, and that some people have little chance to escape their fate.

“You get a bit cold, a bit hard to the world when you choose to become a police officer,” he writes. “Otherwise your heart would simply break There are suicides, sexual assaults, armed robberies and gruesome car crashes.

“The thing that always gets you, though,” continues Webster, “is the kids. Kids growing up in the chaos, moving from filthy apartment to filthy apartment. Kids with welfare moms and prison dads, parents who are too consumed with their own problems or vices or just too distracted to give a damn.”

For this reader, “One Promise Kept” was a realistic, thoroughly absorbing read. While I’ve read other first-person accounts by police officers, I’ve never come across anything like this. It makes you feel as though you’re right there confronting a man with a gun, or trying to separate two women fighting outside a just-closed bar.

Some may find parts of Webster’s book distasteful. Compassionate though he is, the author shows an understandable disgust now and then that’s expressed in common language.

“There were days,” he writes, “when I asked myself why I was shoveling (excrement) upstream, busting my (butt) for junkies who never seemed to get better. I would arrest them and try to help them, only to arrest them a week later for doing the same thing in a different apartment.”

“One Promise Kept” has garnered praise from the law enforcement community. Paul Gaspar, executive director of the Maine Association of Police, calls it “an insightful and poignant view of the other side of the badge that is rarely shared with the public.”

Tom Joyce, a retired police officer turned college professor, characterizes the book as providing “an in-depth understanding of the life of a law enforcement officer.”

You’ll have to read “One Promise Kept” to find how Webster honors his pledge to a 7-year-old. This is a short book with a big punch. 

Lloyd Ferriss of Richmond is a freelance writer.