Submitted photo“Labyrinth” airs tonight and Friday on The CW.

One unfortunate thing that happens these days with historical fiction, such as Dan Brown’s “The Da Vinci Code,” is that some readers are unable to separate the history from the fiction, which does a disservice to both. The best historical fiction starts with fact and then spins out a fanciful tale from the author’s imagination.

Novels are not intended to be history books, but if taken in the right spirit, they can lead the reader to start digging into some real history. If that happened with “Labyrinth,” author Kate Mosse would be very happy.

Tonight and Friday The CW airs production company Scott Free’s 2012 TV miniseries adaptation of Mosse’s 2005 novel that happens in one place — the town of Carcassonne in the southwest of France — but in two eras separated by centuries but connected by a search for the Holy Grail.

Jessica Brown Findlay (“Downton Abbey”) stars as Alais, a 17-year-old in 1209 Carcassonne. Her family belongs to a religious sect known as the Cathars — which blended elements of Christianity, Gnosticism and Manichean duality — that became the target of a Crusade.

Her father entrusts her with a book full of strange words and labyrinth symbols, as well as a labyrinth-engraved ring — and possibly the secrets of the Grail.

Vanessa Kirby plays Alice, a present-day volunteer at an archaeological dig in the French Pyrenees who stumbles across a tomb, carved with labyrinth symbols, that contains two skeletons. That leads her on a quest that unexpectedly links her with Alais’ story.

Also starring are John Hurt, Tom Felton, Tony Curran, John Lynch, Mosse (in a cameo as a modern tour guide), Sebastian Stan, Emun Elliott and Janet Suzman. The medieval scenes were built on location near Cape Town, South Africa, and the modern scenes were shot in Carcassonne.

“We bought a house,” says Mosse, “in the shadow of the medieval city walls of Carcassonne, a tiny house, way back in 1989. I just fell in love with the place and the history and the dark shadows of history that exist everywhere in the town.”

Over the years, Mosse and her husband raised their children both in the U.K. and Carcassonne.

“All of that time,” she says, “I was getting to know the medieval history, this extraordinary story about this Crusade …. I realized that a novel was taking shape in my mind.”

Also central to the idea is the medieval labyrinth, which could be considered one of the first instances of virtual reality. Since most people would never be able to make an actual pilgrimage to the Holy Land, a walk through the complex paths of a labyrinth built near a church or a monastery offered a spiritual pilgrimage instead.

Says Mosse, “More labyrinths were built in France than in all of the rest of Europe. Isn’t that interesting?

“So for me, being a novelist rather than a historian, it’s about finding these extraordinary facts of history or theology, of music or literature or whatever, and spinning a story around why they might have happened.

“That’s what I really wanted to put into ‘Labyrinth,’ the complexity of the way that history and mystery and folklore and religion all get mixed up together in some of these stories about France.”

As to what she thought of the film adaptation, Mosse says, “I think they’ve absolutely captured the spirit of the book. It’s a very long and complicated book to put on the screen; it’s got two different time periods. If it hadn’t been for Ridley Scott (of Scott Free) and some of the people involved … I’ve said no every time I’ve been asked before to sell the rights.

“But with this, they did capture the spirit of it, the idea that there are two women 800 years apart who are linked by a common story, and there are men who love them and support them, who are helping them to achieve that story.”

Mosse also applauds the authenticity of the production.

“The medieval costumes were hand-sewn and hand-dyed,” she says. “The only thing that was freaky was, I’d look at the swords and the shields, and they looked authentic, except when you touched them, and they were so light. If they were real, I couldn’t lift them up.

“I admired that because, in the end, any of us who write stories inspired by history have a responsibility to get the history right, to not play fast and loose with it, because so many people died.

“To have a film company that was determined to get the details of things right meant an enormous amount to me. I was very happy with this and with their passion for the project. I loved the fact that all the young actors came on set with well-thumbed copies of ‘Labyrinth’ and asked me to sign their books. That was the sign of happy filmmaking.”