In The Insane Train, Sheldon Russell's second historical mystery featuring 1940s railroad security agent Hook Runyon, mental patients are transferred across the country by train.

How did you get the idea for your unusual sleuth?

I couldn't write about defense lawyers or New York City cops or the CIA with any legitimacy. I needed to write about what I knew. I went to school in a small town in Oklahoma. It was a railroad town with a Santa Fe roundhouse, depot, switchyards, and the largest ice plant in the U.S. Almost everyone in town worked for the Santa Fe. My father, now age 95, was a machinist for the railroad. That background led to the birth of Hook Runyon, railroad "yard dog." Hook collects rare books, is deadly in a fight, and has an abiding loyalty to his old dog, Mixer. I've known men like Hook. I knew I could write about a guy like this.

Why have Hook live in a caboose?

I needed a sleuth who had a reason to be involved in solving crime, and I needed a way of moving him from place to place without losing consistency among the books, so I had him live in a caboose.

And the plot for The Insane Train?

I was researching something else in the Oklahoma Historical Society when I came across a newspaper article about a private mental institution that had burned in 1908. There were so many victims killed that they were buried in a mass grave. About this same time, the federal government had donated an old fort to the state of Oklahoma. The decision was made to transfer all the surviving mental patients, by train, to the fort. Law enforcement was brought in from all over to make the transfer. My interest in mental issues goes back to an uncle who returned from WWII with mental problems. As a child, I went with my father to have him committed. These elements came together for this book.

What led you to write mysteries?

I was writing historical fiction, which I still do by the way, but it was pointed out to me that my books had a strong mystery element to them. I, too, had sensed this, so I decided to give mystery writing a try. I found that I liked the conflict and suspense that's inherent in the genre, and there's still the freedom to develop character and place. I also had witnessed the enthusiasm and dedication of mystery readers. What writer doesn't want those kinds of readers?