Coherence is a 2013 American science fiction psychological thriller[2] film written and directed by James Ward Byrkit in his directorial debut.

[3] The film had its world debut on September 19, 2013, at Fantastic Fest and stars Emily Foxler as a woman who must deal with strange occurrences following the close passing of a comet.

[5] While Byrkit did have a specific idea for how the film would unfold, he selected improvisational actors and gave them the basic outline of their characters, motivations, and major plot points.

[6] Byrkit told an interviewer, "For about a year, all I did was make charts and maps and drew diagrams of houses, arrows pointing where everyone was going, trying to keep track of different iterations.

"[8] Interviewer Nell Minow confessed her reaction to the actors' relationships: "I just assumed that they all knew each other very well because they fell into the kinds of rhythms that old friends have."

"[8] Reviewer Matt Prigge praised the choice of casting and their actions: "Byrkit ... focuses not on brainiacs, as in Primer, but on smart but mostly under-informed NPR types, who know enough to slowly piece all this together but not enough that they don't usually descend into blabbering, shouting and drinking.

Indeed, Coherence is largely improvised, with a game cast first believably under-reacting to some weird business with laughter and disbelief, then always maintaining a degree of levity (read: jokes and occasional put-downs) even when stuff has gotten real.

"[9] Ryan Lattanzio wrote, "Byrkit brought eight unwitting actors to his Santa Monica home, threw them a few red herrings and set them loose for five days knowing that the film could evolve organically, like great jazz, if he kept his players in the dark.

"[10] Nicholas Brendon, an actor in the film, discussed the improvisational style of the dialogue with Mandatory journalist Fred Topel, who asked: "I understand the way Coherence was done was that everyone got notecards about their characters and the scenes.

Brendon replied, "I can't remember now, but every day we had five different things that we had to convey... but I do know that Jim [Byrkit], and then Alex [Manugian], the other writer, had to make sure that we were all on point.

"We would be right in the middle of the dramatic scenes and there would be another knock on the door that would just scare the hell out of everybody ..."[8] The original score was composed by Kristin Øhrn Dyrud.

And so, we planned the story for a year, including the twists and turns and reversals and betrayals so that we had a really tight puzzle – almost like a funhouse that we knew we could lead the actors through.

"[12] Some reviewers have suggested that Byrkit was influenced by the eeriness of The Twilight Zone and/or the mind-challenging complexities of the science fiction film Primer.

The site consensus says "A case study in less-is-more filmmaking, Coherence serves as a compelling low-budget calling card for debuting writer-director James Ward Byrkit.

"[20] Dread Central commented on the film's themes and wrote, "What's frightening about the story is how willing the characters are to abandon the reality they know in favor of one that may be a little more appealing.

Whether that's a byproduct of the comet and the rift it creates or caused by the characters undermining everyone else around them to get the life they really want is the fundamental idea of Coherence and what makes it so unsettling.

"[21] Clark Collis of Entertainment Weekly praised the film, granting it a B+ rating: "In an impressive big-screen debut from James Ward Byrkit, eight friends discover metaphysics on their menu when a passing comet creates a set of doppelgängers down the road, enjoying their own identical soiree.

The star-free cast is great too, with Buffy the Vampire Slayer vet Nicholas Brendon poking fun at himself by playing an actor who used to be on a TV show ...

[22] Stephen Dalton of The Hollywood Reporter also enjoyed the film: "An ingenious micro-budget science-fiction nerve-jangler which takes place entirely at a suburban dinner party, Coherence is a testament to the power of smart ideas and strong ensemble acting over expensive visual pyrotechnics ... A group of eight friends gather for dinner ... Marital tensions and sexual secrets sizzle just below the surface, but relationship drama is soon overshadowed by metaphysical weirdness when a comet passes close to Earth, shutting down power supplies and phone connections ...

We are definitely not in Kansas any more ... Byrkit only gave his cast limited information about the narrative loops and swerves ahead, encouraging a semi-improvised naturalism that feels authentically tense.

"[23] Ryan Lattanzio of Indiewire praised the film's originality: "Coherence is not just smart science fiction: it's a triumph of crafty independent filmmaking, made with few resources and big ambition.

Gotham-nominated debut director James Ward Byrkit stripped his vision down to the barest of bones to achieve a mind-shifting, metaphysical freakout about a dinner party gone cosmically awry.

"[10] The reviewer for Salon was ambivalent: "After the fundamental problem of Coherence has become clear, or clear-ish – there's another dinner party, at that other house, that looks an awful lot like this one – the movie becomes slightly too much like an unfolding mathematical puzzle, although an ingenious one that reaches a chilling conclusion.

Notes appear before they are written, the significance of those numbered photographs comes into focus through a series of neat twists, and while the characters are half-aware that their actions are being shaped by a space-time continuum whose cause-and-effect relationship has gone awry, that's not enough to stop them.

"[24] Black, a 2024 Indian Tamil language film written and directed by KG Balasubramani starring Jiiva and Priya Bhavani Shankar, is an adaptation of Coherence.