Odds are you will walk out of a screening of Upstream Color scratching your head, frustrated, a little lost. You'll argue about it - What's the film about? - with your companions. With yourself.

Dense, richly textured, and emotionally fraught - uplifting and devastating in equal parts - Shane Carruth's masterful sophomore effort is an abstract, elusive, but emotionally engaging love story that's more tone poem than drama.

It's the kind of film that will invade your dreams.

Carruth, 40, a former software engineer, made a stunning debut in 2004 with his $7,000 sci-fi thriller, Primer, which won the grand jury prize at the Sundance Film Festival.

A stunning, thematically complex, minimalist piece, Primer used time travel as a trope to pose questions about self-identity and moral responsibility.

Both films are true auteur projects - Upstream Color has Carruth do the job of director, writer, producer, cinematographer, composer, coeditor, actor, publicist, and distributor. The new film is far more puzzling and surreal, yet deeply moving.

Unabashedly experimental, Upstream Color features an intense performance by Amy Seimetz (Sun Don't Shine) as Kris, a young, successful visual artist in the film industry. Her life becomes undone one night when a thief (Thiago Martins) force-feeds her special larva he cultivates in his greenhouse that make her susceptible to his commands, as though she were under hypnosis. He never touches her physically, but he makes her sign away all of her cash and property.

After the intruder leaves, Kris is haunted by visions of worms crawling under her skin, and she begins cutting herself. She is healed when a sound designer and pig farmer draws out the larvae from her body using sound.

Years later, after she has been treated for various mental disorders, Kris meets and falls madly in love with Jeff (Carruth). When considered in the context of her budding romance, Kris' bizarre backstory is surprisingly effective as a metaphor for the emotional baggage so many of us carry through our lives.

As their relationship evolves, the lovers seem to fuse into one another - they have each other's childhood memories - and seem to enter a psychotic universe of their own creation.

Carruth portrays the couple's courtship in scenes so evocative they reach heights of cinematic lyricism rarely seen on film since Jean Cocteau's Orpheus (1950). The love scenes are as concrete, physical, and as present as the overall narrative is ambiguous, fleeting, mysterious.

So what is Upstream Color about? It's about love as shared madness, about our troubled, desirous yet equally dangerous relationship with our bodies, with one another, and with the rest of nature.

It's a series of puzzles with no answer that achieves that rare aesthetic peak contemporary art seems to eschew with extreme prejudice: The sublime. It presents us with a glimpse of the vastness of existence, of our inner nature, and of nature without that is as equally dreadful, enveloping, and terrifying as it is beautiful.