For those of us who are more familiar with the P.C.H. (that’s the Pacific Coast Highway), the title of Michael Cuesta’s debut film “L.I.E.” may need some explanation. The L.I.E. is the Long Island Expressway, and 15-year-old protagonist Howie Blitzer (promising newcomer Paul Franklin Dano) sums it up in the film’s first few lines: “On the Long Island Expressway there are lanes going east, lanes going west, and lanes going straight to hell.”

From his first moments onscreen, Howie dares us to guess which way he’s going, even while he’s living the traditional suburban teenage life filled with well-placed angst. In a startlingly natural performance, Dano anchors the film with his precocious but vulnerable vision of a world that’s flying by him.

Cuesta meanwhile works wonders with a cast and crew of first-timers. He captures the life of a not-so-typical teenager confronting NC-17-worthy realities, all with a remarkable subtlety.

Howie introduces us to his world when he matter-of-factly states that his mom was one of the unfortunate souls who took the L.I.E. to hell. She died in a car accident that left Howie longing for her — and experimenting with her make-up. Predictably, he has an abusive father with a young, thong-wearing new wife. Howie also hangs around with a questionable circle of friends who rob houses in their spare time. Life happens to him, like the L.I.E. passing through his seedy suburb (think “American Beauty”), and he gets tossed from friend to love interest to father figure.

From this scandalous material Cuesta might easily have whipped up an after-school special, but he thankfully shows more respect for his actors and never gives what we expected. Howie’s father Marty (Bruce Altman) is blunt and brutal, rather than a comical or overly strict stock character. He passive-aggressively disapproves of Howie’s behavior but allows him a lot of freedom. Like the rest of the world, Marty is caught up in life; he travels through Howie’s own world without much time to chat.

The friends in question are no simple thugs. They exchange quick dialogue, not the vulgar slang that mars most teen films. Their robberies are rapid-fire, shot by a shaky camera and accompanied by a rowdy, noisy soundtrack.

Most importantly each of the three displays a certain depth. Brian (Tony Michael Donnelly) has a streak of pent-up anger, which perhaps comes from being the butt of constant jokes about when he slept with his sister. Scott (Walter Masterson ) comes to Howie’s rescue many times but still displays a certain adolescent machismo. He disapproves of Howie’s relationship with another friend, Gary (Billy Kay II), but carefully avoids more crass slurs about homosexuality.

Gary’s magnetism fills his screen time with tension, exploration, and a childish, tricky sexuality. He and Howie flirt and share cigarettes by firelight (providing cinematographer Romeo Tirone with a charged lighting opportunity). There is nothing smarmy or smirking about this homosexual relationship; it is happily natural and real, thanks to the grounded dialogue and pacing of Cuesta and his co-writers — brother Gerald Cuesta and novelist Stephen Ryder.

Cuesta does depart from this stark tone for occasional heightened effects. Fantasy sequences are loud and boldly colored, and the action slows to a pause for emphatic moments, which contrasts the film’s largely rushing pace.

For example, at the most energetic point of Howie and Gary’s relationship — they’ve conspired to run away to California together — the boys have a wrestling match. Gary ends up on top of Howie, and the world suddenly slows down as the boys’ faces fill the screen in sharp focus. A wad of spit drips in slow-motion, white and suggestive, from Gary’s lips. Such are all of the sexually tense moments in the film — subdued and seductive, with a close camera that seems so real it’s practically intrusive. By contrast, more explicit sex scenes seem like comic background noise.

Swept away by Gary’s charm, Howie helps him steal two antique guns. Enter vengeful gun owner Big John Harrigan, a surprisingly likeable pedophile who moves through Howie’s world. Big John (English actor Brian Cox) is the perfect stranger with candy: he’s old enough and fat enough to be someone’s sugar daddy, but instead he seduces boys with his red convertible, replete with the allusive license plate “BJ”.

Howie’s filial-style interactions with Big John allow Dano a chance to show off his acting chops. Until this point he is so natural we forget he’s acting; we assume he must simply be playing himself. Dano displays hints of vulnerability behind the countenance of a 15-year-old delinquent, a kid who has done a lot of growing up. He’s insecure and still on the defensive. He casually jokes about sex and Big John’s perversion while being very much enamored of it.

Dano has no trouble shouldering these complexities. With his friends, he is king, a man, and Tirone reinforces this with low camera angles that make him appear taller. With adults, Howie is a child — he fiddles with toys, he cries. He displays a willing innocence, even to the corrupt Big John. He recites Whitman and attempts his own puerile seduction by pissing in the great outdoors as he glances over his shoulder at Big John and by reaching over the man’s chest for his backpack.

But most of all Dano is an anchor. His amazing performance carries the film, which is written to rest largely on his shoulders. The other characters — so well-depicted that we want to follow each into his own film — rush by Howie in an endless stream like cars on the L.I.E. Some deceive or betray him; others are forced away, all by that same highway.

Like Howie’s daredevil antics on a beam above the highway, “L.I.E.” perches confidently between childhood and adulthood, between movement and stillness, and most of all between in-your-face reality and tense subtlety.

And at the center of it all is Dano, who will hopefully avoid the lanes straight to hell for the lane to a long, fruitful career.