Stephen King details new film 'A Good Marriage'

NEW YORK, Sept. 24 (UPI) -- Stephen King says A Good Marriage explores the secret lives of loved ones.

The 67-year-old author published the novella in the collection Full Dark, No Stars in 2010, and adapted the work himself for film. The story follows Darcy Anderson (Joan Allen) as she discovers her husband Bob's (Anthony LaPaglia) sinister secret, and King told CBS This Morning he focused the plot on the characters' relationship.

"She never had a clue of what he was doing and this secret life that he had," the writer shared. "And so I started to think, I wonder how many of us are sleeping with strangers and what we really know about the people that we think we're close to."

King said the story was inspired by real-life serial killer Dennis Rader, aka the BTK Killer. Rader was convicted of killing ten people in 2005, and his wife of 34 years claimed to have no knowledge of the crimes. The screenplay is the writer's first since Pet Semetery, which premiered in 1989.

A Good Marriage is directed by Peter Askin, and co-stars Kristen Connolly and Stephen Lang. The movie opens in theaters October 3.