“My books are love letters to Quebec — the language of my characters is French, and I wanted my characters to live in that language,” she said, referring to the belated translation of her books into French. Nevertheless, she conceded that her own French had sometimes failed her. She once ordered “flaming mice” in a Quebec City restaurant, while trying to order “flaming cherries,” and accidentally praised Quebecers as “good pumpkins” rather than “good citizens” at a diplomatic function.

Ms. Penny, who frequently bursts into raucous laughter, says she is still treasuring a literary success that came somewhat late in life — she was 46 when her first novel, “Still Life,” was published after being rejected or ignored by 50 publishers. Nevertheless, she says that experiencing dark times helps her to conjure “the trail of rancid emotions” that prompts her killers to kill.

Her streak of rural carnage, she says, was also partly inspired by a line from “Herman Melville,” a poem by W.H. Auden: “Evil is unspectacular and always human.” She derived further inspiration, she said, from her years covering crime stories — drug wars, biker gangs and murders — for the Canadian Broadcasting Corporation.

The daughter of money managers, Ms. Penny spent 18 years as a radio journalist in Winnipeg, Manitoba; Thunder Bay, Ontario; Montreal and Quebec City. She said that she turned to alcohol to help her deal with a gnawing loneliness, self-loathing and fear that had buffeted her since she was a teenager, and by age 35, had contemplated suicide.

“I had developed an unhealthy worldview, which was that the world is a scary place filled with people who want to or are capable of doing harm,” she said. “I know what it’s like to hate yourself so much that you have to murder yourself. Coming out the other side gave me a profound belief that goodness exists.”

That realization, she said, became the leitmotif of her books.

Ms. Penny credits a call to Alcoholics Anonymous and falling in love with her husband, Michael Whitehead, a pediatric hematologist who died in 2016, for helping to tame her demons. It was a slow, painful process.