All is not what it seems in “The Invitation,” and that’s very much the intention of the lavish new horror-thriller starring Nathalie Emmanuel, of “Game of Thrones” fame, releasing Aug. 26 from Sony Pictures.

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The plot revolves around Emmanuel’s character Evie, who takes a DNA test after the death of her mom, her only known relative, and discovers she belongs to a family of British aristocrats. Her newfound cousin invites her to a sumptuous wedding in the family’s remote English castle. At first enthralled by the handsome lord of the manor, Walter played by Thomas Doherty, Evie is soon thrust into a nightmare of survival as she unravels the twisted secrets in her relatives’ history and the key role that she must play to continue the family’s bloodline.

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“On the surface, it’s this beautiful world but when you get closer, when you look at the finer details, you realize the horror. The beauty is covering a nightmare boiling under the surface,” said director Jessica M. Thompson, an Emmy-nominated filmmaker who made her feature writer-directorial debut with “The Light of the Moon,” winner of the Audience Award for Best Narrative Film at SXSW. 

There are plenty of red flags that make you want to scream “Get out of there!” to Evie, such as the stark absence of the bride and groom. Evie keeps asking where they are, only to receive vague answers, until she realizes, too late, who the bride is.

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She’s instructed not to leave her room, especially at night, and then notices that Walter only seems to have female friends. Evie soon understands that her dream of having a family is turning upside down. “I feel like they’re not telling me something. Why was I brought here?” she asks.

The hints and the dark interior of the manor — the location was the real-life castle Nádasdy, about an hour outside of Budapest, Hungary — build suspense to a dramatic reveal during the ball scene, where the truth is unmasked. The scene took three days to shoot.

Beyond the plot itself, Thompson set out to create an atmosphere rich with subtext throughout the film’s production design to signal that things are not quite right with this family despite their opulent appearance.

Evie’s bedroom, for instance, features a painting depicting beautiful birds. But a closer look reveals the birds are being hunted by weasels. In the ball scene, the decadent food on the tables is actually rotting, melting and dripping, while the gorgeous chandelier overhead is really made of antlers and skulls. 

“There are so many details for the audience to see that are beautiful from a wide shot but when you get to an extreme close-up, you realize everything that is beautiful is also dangerous,” shared producer Emile Gladstone, who also produced 2019 worldwide hit horror film “The Curse of La Llorona” for Warner Bros. and New Line Cinema.

During the ball, guests wear lavish face masks and the scarlet liquid in the wine glasses isn’t exactly Cabernet.

“There are dualities throughout the whole film — nightmare and fantasy, prey and predator, upstairs and downstairs,” Thompson says. “So we’ve tried to capture that in the design, the lighting, the costumes, the performances. All of the sets have a duality, representing both the romance and the nightmare.”

In making the film, Thompson was inspired by the 1972 Rothschild Ball, also known as the Surrealist Ball or Illuminati Ball. Held at Guy de Rothschild’s lavish chateau, the evening began with servants greeting guests by behaving like cats. Guests proceeded from the front door into a maze. Plates were covered in fur, and tables were decorated with taxidermied tortoises and dismembered baby dolls; food was served on a mannequin corpse on a bed of roses. Dead fish accompanied the forks. Salvador Dali designed many of the masks worn by guests and Audrey Hepburn attended in a birdcage draped over her head; Madame de Rothschild wore a stag’s head studded with diamond tears. 

That unexpected shock of luxury disguising danger, beauty overlaying gruesomeness, is exactly the aim in “The Invitation.”

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“The really horrific things in life aren’t actually the things in the dark,” says Autumn Eakin, director of photography. “They’re the things that are right in front of you, but you just haven’t opened your eyes to them yet.”

“The Invitation” is rated PG-13 and releases nationwide in theaters on Aug. 26.