“Outlander” is based on the first book in Diana Gabaldon’s series of best-selling novels, which have sold more than 20 million copies worldwide. Ms. Gabaldon has now written eight books, all of which straddle the genres of historical fiction, romance, fantasy and adventure, and a ninth is on the way. Each volume (many run more than 800 pages) is expected to be covered by one season of the television show.

Ms. Dresbach’s sublime costumes are a starring attraction. Yet before she and Mr. Moore decided to collaborate on the project, she had retired from show business and was spending much of her time helping to raise his two young children from a previous marriage, as he worked on sci-fi series like the highly acclaimed “Battlestar Galactica” revival.

Still, she couldn’t resist the lure of bringing to life Ms. Gabaldon’s best-selling historical novels, which she started to devour soon after the first one was published in 1991.

“As Ron kept pointing out, ‘Who the hell else is going to do this other than you?’ ” Ms. Dresbach said. “He was kind of right.”

It turned out to be a perfect fit. The couple share a similar philosophy when it comes to period costumes: Make them as authentic as possible. “I want them to look lived-in, beaten-up and home-repaired,” Mr. Moore said. To that end, his wife assembled a 15-person aging and dyeing department, whose primary objective is to weather the costumes and “make them look real,” he explained.

Occasionally, they clash when the needs of story and the reality of costumes collide. For instance, when the villainous redcoat Capt. Black Jack Randall (Tobias Menzies) literally rips Claire’s bodice, Mr. Moore said, “Terry tells me in excruciating detail how impossible it is to rip open these dresses unless you’re the Hulk, because there are many layers of thick fabric.”