Spoiler Level: Low

In Looper, a mob-boss named Abe (a scene-stealing Jeff Daniels), living in the year 2044, chastises his young protegé Joe (Joseph Gordon-Levitt) for his retro, 20th century-style fashion sense. "Those movies you're dressing like are just copying other movies," he says. It's a self-aware line, a sly recognition that Looper, itself, is breaking little new ground in its science fiction tropes, in its dramatic set pieces, or in the redemptive arc of its cynical, tough-guy hero. Writer/director Rian Johnson (Brick) is a movie-lover's movie maker: he's neither as flashy nor as shameless a postmodern film geek as—for example—Quentin Tarantino, but Johnson is every bit as happy to be playing in the cinematic toybox, and perfectly content to make exciting new stories from the trusty old action figures and playsets he finds there.

This kind of referential, reverential filmmaking is no sin, and to do it this well is no small accomplishment: there is little we haven't seen before in Looper, but the skill and care Johnson brings to it makes it all feel fresh and original. Appropriate for a time-travel movie, Johnson makes the old seem new again.

"I don't want to talk about time-travel shit," one character says, in yet another self-aware line. "If we start, we're going to be here all day making diagrams with straws." And indeed, the complicated temporal mechanics of Looper are both the hardest elements to describe and the ones that least bear scrutiny. Time travel hasn't been invented in 2044, but by 2074 it's already been invented and outlawed, and you know what they say: when time travel is outlawed, only outlaws will use time travel. In the world of Looper, it's used predominantly for getting rid of problems: murder is almost impossible to get away with in 2074, so the mobsters zap their unwanted people back thirty years to be killed by "loopers" like Joe. Loopers go to a previously arranged spot, lay out a convenient tarp, and wait with a shotgun—a blunderbuss, actually—for the bound and hooded victim to appear.

Shoot the anonymous victim, collect the payoff of silver bars strapped to his back, and dispose of the body: it's an easy job, and a lucrative one, affording loopers a standard of living considerably higher than most people living in the economically devastated mid-21st century. There's a catch, however: loopers are on a short-term contract. Eventually, the victim on the tarp will be the looper himself, 30 years older, sent back from 2074. At that point the looper collects one last, major payday, and goes off to enjoy the last 30 years of his life before one day getting sent back in time to die at the hands of his younger self. This is called "closing your loop." "It's not a job that attracts a lot of forward-thinkers," Joe narrates.

There are a lot of obvious questions about this scenario that are better left unasked, but one of them—why don't loopers simply let their older selves go?—is asked and answered in a fairly convincing way. Joe's fellow looper Seth (a wonderfully pathetic Paul Dano) can't bear to pull the trigger when confronted with his own future self, and lets Old Seth get away. This is where Abe—who was sent back by the Future Mob to run the loopers—earns his money, proving that he has some terrible (and terribly clever) ways to deal with old and young runaways alike.

Before Seth falls back into Abe's hands, however, he comes to Joe for help, but at this point in the story Joe is more about money and self-preservation than friendship. The scene is reminiscent of Ugarte pleading for help from Rick in Casablanca, and that's no accident. (The bar from which Abe operates is called La Belle Aurore, after the spot where Rick and Ilsa began their journey.) At the beginning of Looper, Joe is a cynical, world-wearied loner, cut in the same archetypal cloth as Rick Blaine and any number of other American movie icons; his character arc—from selfish rogue to reluctant hero—constitutes the emotional structure of the story.

It's to Johnson's credit, however, that such standard fare never feels as simple and tired as it should in Looper. The situation becomes more complicated when Joe's future self (Bruce Willis) finally arrives to close the loop, and manages to escape his pre-assigned fate. Now Young Joe has to recapture his older self, or face a terrible retribution from Abe. Old Joe has a sad back story and some good reasons to want to change both of their futures, and for much of the movie we're honestly not sure who we're rooting for: despite some slightly counter-productive make-up effects (to make Gordon-Levitt look more like Willis), it is easy to see the similarities in the two men. Neither is wholly good or wholly bad, wholly right or wholly wrong, and thus embody one of the simple but effective themes that runs throughout Looper: the potential we each have within us for goodness and evil, for sin and redemption. A lesser writer might have made one Joe good and the other bad, but Johnson understands that human nature is more complicated than that, and that character development—like time travel—is hardly ever linear.

Without giving too many of Looper's many surprises and pleasures away, I'll just say that Old Joe's mission in the past—and Young Joe's mission to set things right—end up placing in danger a single-mother named Sara (Emily Blunt) and her five-year-old son Cid (Pierce Gagnon). This long segment of the film, which takes place in a field-surrounded farmhouse, also draws comfortably on any number of cinematic predecessors—most notably Witness—but Johnson's remarkably patient screenplay and direction give the familiar tropes and predictable beats of Looper remarkable texture and immediacy. (Of the actors, Blunt is particularly good and making what could have been a cardboard character into a real woman about whom we can care. And Johnson gets a remarkably good performance out of little Pierce Gagnon, as the damaged child who may—or may not—be the key to changing the future.)

When a sci-fi movie comes along that manages to be intelligent, restrained, and still a hell of a lot of fun, it is tempting to overstate its worth, and Looper is not quite a masterpiece. The basic silliness of Johnson's premise here is slightly at war with the maturity of his filmmaking, and Looper sometimes feels like a lesser B-movie unnaturally elevated into an art house thriller. Johnson evokes more interesting themes than he actually ends up exploring, and his many small ingenuities are ultimately in service of a very familiar, old-fashioned story. (I also find Gordon-Levitt to be a competent but surface-level actor: it is tempting to imagine what Dano might have done with the lead role in this film.)

Still, as with Duncan Jones's similarly mid-level 2011 triumph Source Code, it is probably better to praise Looper for its considerable successes than fault it for its lack of ambition. I can regret that Looper didn't quite blow my mind, but I can also appreciate that it didn't insult my intelligence either. I strongly suspect Rian Johnson is one or two films away from making a real masterpiece, but until then we can be happy to have Looper, a smart, self-aware sci-fi thriller. It may be an amalgamized copy of several more visionary movies, but—when the copy is this good—somehow you don't mind so much.