It has been a long time since Karyn Kusama has gifted us with a film, six years to be exact. She’s had a spotty track record too. After her breakout film Girlfight in 2000, Kusama faced critical and commercial failure with the 2005 Charlize Theron film Aeon Flux. In 2009, all hope seemed lost with Jennifer’s Body, another commercial failure (critics were mixed, though I actually enjoy that film). Now, Kusama presents us with The Invitation, which screened at Fantastic Fest in Austin, TX on Sunday. It may very well be her strongest directorial effort to date. Co-written by her husband Phil Hay and his writing partner Matt Manfredi, The Invitation is a brilliant film that will have the audience feeling uneasy until it’s heart-pounding climax.

When the film opens, Will (Logan Marshall-Green, Prometheus) and Kira (Emayatzy Corinealdi) are driving towards the house of his ex-wife Eden (Tammy Blanchard, Into the Woods, Blue Jasmine) and her new husband David (Michiel Huisman, World War Z, Game of Thrones), where they have just been invited for a dinner party serving as a reunion for old friends. Eden ran off to Mexico two years prior, after the death of their son, cutting off all contact with her friends and family. Will begins to notice that something seems off about Eden and David’s behavior. Over the course of the film’s 97 minutes, we sit back as guests to the dinner party as Will’s paranoia over Eden and David’s strange behavior begins to throw everything into chaos.

To say anything more about The Invitation would truly spoil this fantastic gem of a film. Of course, it is best walked into knowing little to nothing about it, but that is so difficult nowadays when trailers spoil entire films.

Aside: Director Karyn Kusama was present for a Q&A after the screening and asked (along with a Drafthouse Films representative) how they should market the film. They even took suggestions from the audience on what kind of trailer to cut. I can only hope they listen to our suggestions when the film is released next year. End Aside.

The Invitation is deliberately paced. That is not to say it is slow (though some might say that), but it is best viewed as an examination of the different ways that people handle the grieving process. This is Kusama’s strongest directing effort to date. The way The Invitation is shot creates some of the most unbearable tension I’ve ever felt in a film.

For much of the film, we are constantly second guessing ourselves over what is actually happening at this dinner. Do Eden and David have something insidious planned? Is Will just overly paranoid and letting his grief over his son’s death get the better of him? Or are we watching some weird social experiment? By the third act, all questions are answered, but the film never loses steam and the tension carries over all the way to the final shot.

Performances are strong all across the board. Marshall-Green, a dead ringer for Tom Hardy, plays the tortured soul well. Blanchard and Huisman are great at making the audience feel incredibly uneasy about their motives. The standouts for me were Corinealdi, who is in the difficult role of “the new girlfriend” and Michelle Krusiek as the wild party girl in the group of friends. Of course, you can’t forget about John Carroll Lynch, whose role in the film evokes his similar role in Fincher’s Zodiac.

The Invitation may very well be one of the most unsettling films I’ve ever seen. It works in so many ways and is a tour de force from Kusama. Here’s hoping she stays directing genre films. It will get a release sometime in 2016 so make sure to seek it out when it does.