Certainly this spry sci-fi puzzler sets a new bar for little indie movies about young white couples having dinner parties and sorting through their romantic angst. On this occasion, heartaches and head games get even more complicated by the quantum-mechanical upheaval of a passing comet: Our company finds itself on a roulette wheel of alternate realities, and, like a game Star Trek crew, does its best to troubleshoot. As you might expect, lacking experience with this sort of thing proves to be a dramatic accelerant. Its setup being vaguely Buñuelian, Coherence might have been braver about letting surreal silences play, but writer-director James Ward Byrkit was shrewd to make talking through conceptual exposition seem like a situation-appropriate nervous habit. It's also unexpectedly useful that his cast of eight, led by Emily Foxler, comes across at first as a little vanilla — collectively a clean blank page just calling out for some elaborate scribble. Byrkit's is an exactingly proportioned blueprint for well-paced cerebral freakouts, downplayed humor, and the humblest of special effects, not to mention the robust cult fandom that attends similarly resourceful sci-fi trips like Primer. It's all great fun, and a tribute to what's possible with the modest means of earthbound materials and a cosmic imagination.