Review: 'The Housemaid' is a thriller with twists and steamy sex scenes — but it's the back-and-forth between stars Sydney Sweeney and Amanda Seyfried that turns up the heat.

Part psychological thriller, part revenge thriller and part erotic thriller, “The Housemaid” does a good job of keeping the audience off balance because the script leans in so many different directions, most of them entertaining.

The protagonist, at least when we start, is Millie (Sydney Sweeney), a young woman who seems overqualified for the job of live-in housemaid, which is what she’s applying for with the rich Nina Winchester (Amanda Seyfried). We soon learn the reason Millie so eagerly accepts the job: She’s living in her car, and she’s out on probation and will go back to prison if she’s not gainfully employed.

But working for the Winchesters turns out to be more difficult than advertised. Nina’s daughter, Cece (Indiana Elle), is a sourpuss who doesn’t like anything Millie does. And Nina turns out to be demanding, and getting into screaming rages when things aren’t exactly as she wants them — with Millie being the main target of that anger. The upside is that Nina’s husband, Andrew (Brandon Sklenar), is hunky and a perfect gentleman.

After Millie learns more things about Nina — mostly from the gossiping PTA ladies in Nina’s neighborhood — you get a good sense of where this movie, based on Freida McFadden’s novel, is going to go. And, for a bit, the prospect of a furtive romance between Millie and Andrew seems very much in the cards. When things heat up, the movie earns its R-rating with some steamy sex scenes between Sweeney and Sklenar.

But that’s not the end of the story, and director Paul Feig (“A Simple Favor”) and screenwriter Rebecca Sonnenshine (an Emmy nominee for “The Boys”) pull out some twists from McFadden’s playbook that show Millie isn’t the only one who’s pretending to be what they’re not.

Some of the reveals are genuinely suspenseful, while others get telegraphed well ahead of time. Sweeney and Seyfried have the most fun, as their roles and perspectives shift through the narrative, and Sklenar puts his smoking-hot good guy persona — put to good use in “It Ends With Us” and “Drop” — through the ringer in some entertaining ways.

“The Housemaid” is purely a pulp potboiler, and it’s a delight to see a movie with nothing on its mind than messing with its audience, giving them some prurient thrills, and sending them home howling at the outlandishness of it all. 

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‘The Housemaid’

★★★

Opens Friday, December 19, in theaters everywhere. Rated R for for strong/bloody violent content, sexual assault, sexual content, nudity and language. Running time: 131 minutes.