Shane Carruth's new movie could leave you even more bewildered than Primer

Nine years ago, writer-director Shane Carruth left Sundance in awe with Primer, a time travel film that was simple in production but insanely complex in its plot. Primer took a basic set-up, a time machine, and managed to turn a low-budget film into one of the smartest, and also scientific jargon-filled movies in recent memory. Now at last, his second film Upstream Color just showed at Sundance. How does it stack up?

Some spoilers ahead...

With Upstream Color, Carruth ditches the jargon and definitives for hypnotic hallucinogens, synchronized movement, amps pulsating sound into the ground, pigs, more pigs and mind-melds. It's trippy and fascinating — and like Primer, it's the kind of film that will lead to endless discussion after seeing it.

The film's logline says the story involves "a man and woman [who] are drawn together, entangled in the life cycle of an ageless organism." That's somewhat true, but also very misleading. Upstream Color is without a doubt a science fiction film, but not one about lasers or space travel. It's part character study, part treatise on identity and what remains after everything is stripped away. There are a few key ideas, such as hallucinogenic worms, that set up the story, but the film uses those ideas more to examine its characters than to propel a plot forward.

The film hinges on Kris (Amy Seimetz), who finds herself a victim of a twisted theft. And thankfully Seimetz manages to bring a lot of emotion to the role, mainly through body language in some of the film's many dialogue-free scenes. Her range is incredible, from a hypnotized captive to a crazed survivor overcome with unexplained sensations. Carruth, who joins in the second act and has as many of his own personal secrets as Kris, matches Seimetz's body language scene for scene. Their physical chemistry — not through sex, but through a way of carrying themselves that says just as much as any dialogue would — not only deepens their relationship, but adds an eerie element when visions and sensations start to overlap between the leads.

Shane Carruth's new movie could leave you even more bewildered than Primer

Carruth said he was focused more on creating an "architecture," or a world that the film could inhabit. Even with as simple a science fiction concept as these worms, the reach of their influence, from farmers, to thieves to pig farmers, shows a world both familiar to reality but also clearly its own. The ideas Upstream Color brings up are fascinating, and Carruth's vision of them are rendered in beautiful audio and visual.

Upstream Color is both linear and yet not. The overall story flows from beginning to end, but each scene is a montage, filled with repetition, expanded lines, different angles and increased clarity each time they are shown. Carruth centers on parallels – be it audio or visual – to string these together, leading to moments where the film is more of a sensory experience rather than a cohesive narrative. It's cyclical, because Carruth said "the cycle is the construct." That's not bad, since Carruth's cinematography is a soft, color-filled window into the world. Instead of muted colors out of Instagram, the movie is bright and rich, a visual treat that doesn't rely on sharp, crisp frames to bring tension. The music, which cuts from diagetic to non-diagetic, and absent to overpowering, drives the movie at times, and instead of being distracting, acts more like Carruth's not-so-silent hand, gripping the audience and bringing some of the film's extreme ideas to life.

Shane Carruth's new movie could leave you even more bewildered than Primer

But as brilliant as some of these ideas are, and as strong of an architecture that Carruth constructs, the plot fails to come together. The montages are fascinating, but both plot elements and dialogue are sparse. In many ways, the acting and direction convey the concepts, but much goes unexplained, either in time skips or in some moments that just aren't shown. There's one major interaction at the end of the first act, in an otherwise disturbing and yet eye-catching sequence, that isn't set up and goes completely unexplained.

Shane Carruth's new movie could leave you even more bewildered than Primer

The film can be trying. At times, if it wasn't for Carruth's crazed, imaginative montages, you might think Upstream Color is just slipping away from its plot. But his mastery of using the medium to suit his themes keeps it running strong. In exchange for patience, Upstream Color rewards viewers with a brilliant movie that uses the screen in a way few other films can.

Carruth's sophomore work isn't as strong in terms of plot as Primer. But it has heart, that comes from its strong performances and its visual style. It's a great exploration of the nature of identity and relationships, and not in traditional ways. It's definitely not for everyone, but Upstream Color shows not only Carruth's genius as a filmmaker, but just what kind of personal stories science fiction can tell.