John Lyman is working on a screen adaptation of his book.

Courtesy of John Lyman

One sunny tropical day in Hawaii, retired nurse John Lyman lay on a beach and read about a code mathematicians had spotted in the Bible. Inspired, he jotted down about 20 pages of a story, which ended up in a drawer in his guest room when he got home to Tucson.

His mother discovered it on a visit, and, wanting to read to the end, told him to finish it.

“So being a good son, I did what I was told.” Lyman said.

He finished “God’s Lions: the Secret Chapel” in 2009 and has since written three more in what became a series that’s available on Amazon’s Kindle. The fourth, “God’s Lions: Realm of Evil” was released Dec. 1.

Lyman’s wife, Leigh Jane, had remarked that if the right person picked up the book, it could make a really good movie. Those proved prophetic words.

“I got some fan mail,” Lyman said, “and one of the people who wrote me said her husband happened to be a producer. She said she woke up one night and he wasn’t in bed, so she went looking for him, and he was downstairs reading my book. She said he couldn’t put it down.”

That reader was Peter G. Kuys, chairman of Kuys Entertainment Group, an independent production company based in the United Kingdom that has just begun development on the first “God’s Lions” book. Kuys’ past projects include “The Crying Game” and “Weekend at Bernie’s II.”

Lyman is now part of a screenwriting team with Christopher Cibelli, an editor on the CBS series “The Mentalist,” and Cindi Grossenbacher, the show’s script coordinator. He said the collaboration has been a lot of fun, but it has also been a learning experience.

“You can’t just have pages and pages of dialogue like you do in the novel,” Lyman said. “You have to cut it down for the actors. The hardest thing is to realize that I’m writing for a visual medium rather than someone who’s reading a book.”

In this stage, the screenplay is being written while the producer searches for the right director and other staff members. Much of the action will be determined by the director, Lyman said, but he’s not worried about the story being changed when it gets to movie form.

“The executive producer (Kuys) is adamant that we don’t change the story,” Lyman said. To help with this, Lyman said the director will be working both from the screenplay and the book itself.

At this early stage, Lyman said it’s hard to know whether a big-screen future is in store for the rest of the “God’s Lions” series. But after spending two years on the first book and about a year on each of the next ones, Lyman said he’s going to let these simmer for a while.

“I’m not going to say goodbye to the characters,” he said, “but I just kind of needed a break.”

So, other than writing a screenplay with professionals from San Francisco to London, what is he doing for a break? Working on a different novel — and this time, he’s going back to his Texas roots with a female protagonist from a small town. It’s a bit of a change, but it will still be a thriller, Lyman said — just a little more like Michael Crichton and a little less like Dan Brown.

So after four novels, with a fifth and a movie on the way, a 35-year career in nursing and six years in law enforcement, it seems strange to think of Lyman as “retired.”

“Good point,” says Lyman. “Guess I’ve just started a new career.”