The formula for the Hollywood romantic thriller is fairly consistent: In a moment of weakness, a husband cheats on his wife with another – often younger – woman, only to regret it days later when the one-night stand begins to wreak havoc on what was otherwise a loving relationship.

Sometimes, there are subtle changes to the story line. Perhaps the other woman is the babysitter or a co-worker, or maybe the gender roles are switched. But historically, never are any of the main characters black.

In recent years, however, Hollywood has been recasting a genre that had been the province of white stories – think “The Hand That Rocks the Cradle,” “Fatal Attraction,” “Single White Female” or “Unfaithful” – for black audiences. (And when those love-triangle potboilers with white casts do get made, they are made-for-TV B-movies, not A-list theatrical releases. See countless Lifetime flicks.)

Last weekend brought “When the Bough Breaks,” Sony-Screen Gems’ new provocative thriller led by Morris Chestnut and Regina Hall as a successful couple who, unable to conceive a child, hire a beautiful young surrogate (Jaz Sinclair) to carry their baby. There are potentially deadly consequences, though, when Sinclair’s character becomes obsessed with the soon-to-be father. “Bough” brought in an estimated $15 million in the U.S and Canada, less than a projected $22 million but still healthy given its $10 million production budget.

Before that came 2015’s “The Perfect Guy,” starring Sanaa Lathan and Michael Ealy, and 2014’s “No Good Deed,” with Taraji P. Henson and Idris Elba, both from Sony-Screen Gems. The studio was not available for comment on this story.

There also was 2014’s “Addicted,” starring Sharon Leal and Boris Kodjoe, 2013’s “Temptation: Confessions of a Marriage Counselor” with Jurnee Smollett-Bell and Lance Gross and 2009’s “Obsessed” with Elba opposite Beyonce Knowles.

As Hollywood abandoned the mainstream adult thriller to chase either billion-dollar tent-pole films or Academy Awards, it left behind a void that these filmmakers were happy to exploit. Because you still can make money on movies for grownups.

“The beauty of films like these is that generally they don’t cost a lot to make,” said Paul Dergarabedian, a senior analyst with ComScore. “You’re not talking about an outer-space epic where you need $100 million to make it convincing. You just need strong characters, interesting moments and an overall suspenseful vibe.”

“The Perfect Guy,” which cost $12 million to produce, grossed $60.2 million worldwide, five times its price tag. “No Good Deed” cost $13.2 million to make but pulled in $54.3 million globally. And that doesn’t include what these films go on to make once released on home video and into cable syndication.

“In every era where you see a spate of films emerge starring black casts, some kind of conscious awareness in Hollywood is happening,” said Stephane Dunn, director of the Cinema, Television and Emerging Media Studies program at Morehouse College in Atlanta. “It’s a little late to the party, but it’s like, ‘Hey, producing and marketing films to black audiences actually works. It’s a money-maker.'”

The success of this budding genre is due in large part to two phenomena: the dearth of theatrical releases catering to black audiences and the way black romantic thrillers borrow ideas from other genres.

Dunn noted that although black characters were present in “steamy, sexy thrillers” before – see Martin Lawrence’s 1996 film “Thin Line Between Love and Hate” with Lynn Whitfield or director Rob Hardy’s 2000 “Trois” franchise – film representations of black romance as a whole have disappeared. The heyday of “Love Jones” and “Love & Basketball” are gone, she said. As such, when a film does show an inkling of black love, audiences respond.

“It’s the same thing we’ve been saying, that we’re still largely stuck being hungry (for more films with black people),” she said. “And because we don’t have that many other (films), those that do get out there get a lot of attention.”

Dergarabedian added that the black romantic thriller also has aspects of suspense to which audiences, especially this past summer, have flocked – films such as “The Purge: Election Year,” “The Shallows” and “Don’t Breathe,” all low-budget thrillers, have been box-office successes.

“Movies like ‘When the Bough Breaks’ and the rest in this genre serve a specific need that audiences have that combine elements (of different genres),” he said. “It’s a tried-and-true tradition.”

Studios still seem surprised when audiences flock to black romantic thrillers, although they shouldn’t be, said Jeff Clanagan, president of Codeblack Films, a Lionsgate company. Codeblack produced “Addicted,” which was adapted from an erotic novel by New York Times bestselling author Zane.

“One of the biggest book genres for black women is erotic novels,” he said, as evidenced by Zane’s books – more than a dozen of which are New York Times bestsellers – having also been adapted into a number of popular televisions series. “Knowing that there is an audience there already reading these books, it shouldn’t be surprising that now that a movie is being made, they’re coming out to support it.”

But as welcome as it is to have contemporary stories about black relationships, there is always the danger that, in success, this kind of pulpy, lurid entertainment will be all Hollywood wants. Dunn hopes that this box-office beachhead can be used to usher in a “more diverse range of possibilities dealing with representations of black people and sex and sexy, mature relationships.”

“We’re glad to see a Morris Chestnut working,” Dunn said, “but at the same time, we’re hoping for wider treatment and possibilities of what black women-black men relationships can look like.”