For those who found themselves perplexed beyond belief by Shane Carruth’s 2004 debut feature, the infinitely mind-bendy time-travel yarn Primer, his long-awaited follow-up Upstream Color is not nearly as difficult to keep up with — although it’s still not easy to sort out by any means.

Abstraction isn’t easy for people to digest — sometimes because they suspect an artist is trying to pull a single-red-dot-on-white-canvas con job on them, sometimes because they just don’t want to spend money on something that might leave them feeling inadequate to the analytical task. But Upstream Color tells a story that’s accessible even as it pushes in multiple thematic directions. It’s a genre film wrapped in a love story dipped in the avant-garde.

After all, it’s hard to imagine something that immediately screams “artsy-fartsy” less than a mysterious larva that causes people to become the psychological puppets of a vast conspiracy of fraud. Kris Fisher (Amy Seimetz) is just the latest victim, forced by irresistible suggestion to turn over everything of value she owns, only to awaken with no knowledge of what happened and convinced she must be mentally ill. A year later, a still-traumatized Kris meets a man named Jeff (played by Carruth), and they tentatively begin a relationship that’s complicated by even more than the events from her past.

Carruth lays his foundation in a brilliantly chilly first act, focusing on Kris’ ordeal. The affectless voice of the Thief (Thiago Martins) somehow makes the situation even more unsettling, a psychic rape taking the form of rituals so formalized that they’re simply a business transaction. And even as the process takes even more bizarre turns — including a character identified only as the Sampler (Andrew Sensenig), who takes a break from recording sound effects to perform a surgery that links Kris’s psyche to that of a pig — there’s still the horrifyingly human moment of Kris waking up in her car by the side of the road, finding herself injured, and instinctively reaching between her legs under the assumption that the assault must have been sexual.

That human side grows even stronger as the story comes to focus on Kris and Jeff’s relationship. In part, Upstream Color turns into a fairly straightforward allegory for wounded people trying to figure out whether their wounds will allow them a chance at happiness, but Carruth’s Terrence Malick-esque non-linear editing style — the dialogue often repeated, or out of synch with a scene’s images — allows that idea to unfold without ever feeling like it’s part of a lecture.

The approach permits viewers to become immersed in the characters’ world of lost memories and disjointed impressions carried over from their ordeals, their minds so unstable that it becomes impossible for them to know whether the stories they’re remembering are even their own. Post-traumatic stress has rarely seemed so genuinely haunting.

Yet there’s still that freaky business involving pigs, and the Sampler’s ability to continue invading the lives of these survivors, and the process by which a grub becomes a parasite becomes genetic information passed on to a piglet becomes a chemical altering the makeup of a rare flower. Carruth’s wrestling with another notion here — the disconnect between humans and the rest of the natural world, as well as with one another—and he doesn’t exactly play subtle with that subtext as he makes Thoreau’s Walden a key part of his characters’ psychic baggage, and ends on an image that’s bound to leave some viewers snickering rather than caught off guard by its naked emotion. Maybe another viewing will reveal further connective tissue between Upstream Color‘s two key undercurrents of nature and trauma, rather than leaving them as ideas that merely exist side-by-side.

Then again, perhaps it won’t. We also don’t need to be afraid of work that might ask us to engage with it a second or third time in an attempt to reach that conclusion, that doesn’t surrender all of its power at first glance. Even then, it’s still possible to revel in the masterful construction by a filmmaker who tries to tie science fiction, human drama, and bold philosophy into a single mesmerizing package.