Jamie Dornan and Dakota Johnson go darker in Fifty Shades sequel

Cast members Jamie Dornan (left) and Dakota Johnson pose at the premiere of the film Fifty Shades Darker in Los Angeles, California, on Feb 2, 2017.
Cast members Jamie Dornan (left) and Dakota Johnson pose at the premiere of the film Fifty Shades Darker in Los Angeles, California, on Feb 2, 2017. PHOTO: REUTERS

LOS ANGELES (AFP) - Two years after the bonkbuster film Fifty Shades of Grey had housewives reaching for the smelling salts, its sequel reunites Christian, Anastasia and a variety of tools that really ought to be kept in a riding stable.

Northern Irishman Jamie Dornan and US actress Dakota Johnson return as the kinky couple in Fifty Shades Darker, the next installment of E.L. James's bestselling "mommy porn" novels.

Expanding on events set in motion in 2015's box office smash that opened on US$85 million (S$120 million) in the United States and grossed more than US$571 million globally, the movie hits US theatres on Feb 10 - just in time for Valentine's Day.

Expect another heady blend of erotic submission, bondage and ball gowns as James Foley takes over the director's chair from Sam Taylor-Johnson, who reportedly clashed with the author during the filming of the original.

The follow-up picks up where we left the characters, with a wounded Christian Grey trying to entice the cautious Ana back into his life as shadowy figures from his past start to circle.

"We pull out all the stops," Dornan, 34, told reporters as Hollywood rolled out the red carpet for the premiere at the Ace Hotel on Thursday (Feb 2).

"If you're making a sequel to anything, I think there has to be some kind of advancement on the first," he said.

"You have to go a bit bigger in a lot of areas and I don't think this film's any different."

Foley shot Fifty Shades Darker and the final installment, Fifty Shades Freed, simultaneously, with the threequel slated for a 2018 release.

Dornan, who has two young daughters with wife Amelia Warner, has become a worldwide sex symbol since the first movie, but insists his role hasn't influenced his sex life.

He told GQ Australia's February edition that bondage "doesn't float my boat," although he added: "I've always been open-minded and liberal - I'd never judge anyone's sexual preference."

Universal has been shrewdly building anticipation with not-safe-for-work trailers involving underwear being jettisoned at dinner and a raunchy, hands-on display in an elevator.

The marketing appears to be working, with the film topping social media buzz with 246,000 new conversations last week, according to data analyst comScore.

That's 86,000 more than the next most talked-about movie, Star Wars: The Last Jedi.

Don't expect it to achieve the Star Wars-sized numbers that the original managed, however, as it has competition from Lionsgate's action sequel "John Wick" and the hotly anticipated Warner Bros release "The LEGO Batman Movie."

Pre-release tracking suggests Fifty Shades will open in the US$35 million to US$40 million range, still a big win for a movie made for around US$55 million.

Several support actors are returning from the original, including Marcia Gay Harden, who won an Oscar for her portrayal of painter Lee Krasner in Pollock (2000) and the British singer Rita Ora.

They are joined by a cast of newcomers including Kim Basinger - another Oscar-winner - as Christian's ex Elena, the woman who introduced him to BDSM.

Bella Heathcote, 34 years younger than Basinger, plays another ex, Leila, while Eric Johnson is Ana's new boss, Jack Hyde.

Johnson told NBC's Today show on Wednesday that she felt more comfortable filming the sex scenes this time around.

"It's never really easy, but this time it was definitely not completely uncharted waters, Jamie and I obviously having known each other for a long time now."