Eight Los Angeles friends gather for an ordinary meal, which is then

Eight Los Angeles friends gather for an ordinary meal, which is then interrupted by a mysterious crisis. That film was last year’s It’s a Disaster, the occasion brunch, and the outside menace some kind of plague. This time around, in James Ward Byrkit’s modestly suspenseful thriller, it’s a dinner party that happens to coincide with a comet passing close to the Earth. (No, it doesn’t awaken the dead and turn them into zombies; I’ll stop your supposition right there.) The four couples spar a bit and hint at some past sexual intrigue, but they’re a calmer, less neurotic ensemble than that of It’s a Disaster. The vibe is one of settled, contented 30-something-dom: mortgages, Priuses, and careers. These people are more than a little complacent and self-satisfied, in need of a jolt.

Then cell phones stop working and the Internet goes down, the universal tokens of crisis in any modern disaster movie. Soon the power is out, and our eight bumblers are navigating by candles and glow sticks (perhaps left over from that planned trip to Coachella that was canceled for a weekend of shopping and spa-going instead). What’s happening? One guy makes a worrisome reference to something his brother, a physicist, had warned about. They send a search party to the one house outside that seems to have electricity, but this only complicates matters—perhaps by a factor of two, maybe more on a logarithmic scale (I stopped counting at a certain point).

Certainly there’s been an indie trend toward smart, low-budget sci-fi since Darren Aronofsky’s Pi debuted at Sundance ’98 (e.g., The Signal, Safety Not Guaranteed, and the forthcoming The One I Love). Without the expensive crutch of CGI and special effects, however, your script has to be airtight. Byrkit doesn’t have the option here of cutting to alien invaders or the White House being blown up, even if he wanted to. Locked into its one-bungalow location, Coherence is essentially a chamber drama where, most problematically, the writer let his cast improvise the script. Byrkit gave them an outline, then the ensemble ad-libbed during five nights of shooting.

Such liberty is perilous for sci-fi. If anything can happen (aliens, alternate reality, “quantum decoherence,” etc.), the story has to be controlled, thought through to the very last line. Instead we get shaky dollops of post-Lost paranoia (“We’re in a different reality here”), urban folklore, Schrodinger’s cat, and references to Gwyneth Paltrow’s Sliding Doors. I’m spoiling nothing to say that a giant monster doesn’t arrive a la Cloverfield to settle things by stomping Los Angeles into ruin. But Coherence would be a much better movie if it did.

Runs Fri., July 18–Thurs., July 24 at Grand Illusion. Not rated. 89 minutes.