Warning: The following film review contains some minor spoilers.

Director Stefon Bristol's See You Yesterday is something of an anomaly in the pantheon of time travel movies, straddling multiple genres. With its central tragedy, theme focused on the unintended consequences of new technology, and strong social conscience, it's more Black Mirror than Back to the Future. As such, it fits nicely into a small subgroup of quietly innovative time travel films like 2012's Safety Not Guaranteed.

The premise: two teenage science nerds in the Flatbush neighborhood of Brooklyn build a makeshift time machine to right a tragic wrong. C.J (Eden Duncan-Smith) and her best friend and fellow science whiz Sebastian (Dante Crichlow), nicknamed Bash, have just wrapped their junior year at the Bronx High School of Science. They're putting the finishing touches on a pair of portable time travel devices for an upcoming science fair, and they're naturally ecstatic when they succeed on their next attempt at a Temporal Relocation Test, traveling back one full day.

That light-hearted tone quickly turns dark. In an all-too-familiar scenario, C.J.'s older brother Calvin (the rapper Astro) runs afoul of a trigger-happy NYPD officer, who mistakes Calvin pulling a cell phone out of his pocket for a weapon and shoots him dead. C.J. figures she and Sebastian can use their science project to travel back in time to save Calvin. Who among us wouldn't want to try to reverse such a tragedy? But as you might expect, there are some serious unintended consequences to her plan.

"We're very free in how we express to each other. It doesn't mean we're troublemakers."

See You Yesterday is Bristol's first feature film, based on a 2017 short film co-written by Fredrica Bailey and featured at the American Black Film Festival. Bristol was a graduate student at New York University's film school when he wrote the initial script in 2014. Originally, the film was going to be about a young teenager building a time machine to save his friend from being killed by a drunk driver, but a couple of real-life tragedies changed the focus.

In July of that year, a young black man named Eric Garner died after being put in a chokehold by a police office on Staten Island. One month later, 18-year-old Michael Brown was shot and killed by police officers in Ferguson, Missouri. Those killings (plus several others since) and the wave of protests they sparked bled into the script Bristol was writing. His professor advised him to either take out a powerful scene dealing with police brutality, since it didn't fit with the rest of the developing narrative, or make that the main story.

In the final version (which was produced by Spike Lee and debuted at the 2019 Tribeca Film Festival), those tensions play out in a series of note-perfect escalating scenes demonstrating just how easily, say, an innocent, yet intense, argument between a brother and sister on a street corner can be misinterpreted by patrolling police as a harbinger of violence—simply because it involves a young black man. It's the kind of situation black men like Bristol face nearly every day. "Not only my skin color, but the lack of understanding of my culture, will manipulate officers to think that we are prone to violence," said Bristol. "It's just black people being black people. We're very free in how we express to each other. It doesn't mean we're troublemakers, it doesn't mean we're crazy. It's just the way we do things."

Bristol was born and raised in Brooklyn and so were many of the cast members: Astro, Duncan-Smith, and Crichlow, for instance. The director wanted them all "to be authentic, unapologetically black," representing a broad swath of the people you'd meet on any given day walking through Flatbush. Calvin is tough and street-smart—and super-protective of his hot-tempered, whip-smart younger sister, whether she likes it or not—while Sebastian is a good-natured gentler soul. There's the swaggering Lothario, the sweetly acerbic granny, the nerdy science geek with a crush, the strict but loving single mom, and yes, a couple of young men who rob a convenience store. That diversity is intentional. "There's different layers of what being black is in New York, and the country as well," the director told Ars. "Those are just different ways of being black."

While this is technically a time travel movie, the trope is more of a framing device, not the heart of the film. In other words, don't expect it to adhere to real-world physics. See You Yesterday does have its own underlying set of rules that impose constraints and help drive the narrative, though. Bristol deliberately avoided watching other time travel movies so as to not become unduly influenced by them. He read a few books about time travel and time machines, and the director then chatted with a physics professor at NYU about how best to handle that aspect of the narrative. "At the end of the discussion, he said, 'Hey man, time travel is not real. You can make up your own rules,'" Bristol said. "I'm not a STEM expert, and I don't need to be. I just wanted to tell a story about these kids."

"Make the most of your future, because the future is wider than you think."

Among the constraints explicitly spelled out: there's a limited number of times the teens can travel back in time, and there's only so far back they can go. Bristol admits there was originally a lot more (fictional) technical details about how the time travel device worked and what the specific rules would be. But in the editing room, he and his film editor, Jennifer Lee, decided there was just too much expository dialogue. Much of that was taken out to focus on the central story—and the underlying message: all actions have consequences.

That theme is articulated early on in a cameo by Michael J. Fox (Marty McFly himself) as C.J. and Sebastian's science teacher, Mr. Lockhart. He asks them to ponder the ethical and philosophical complexities inherent in time travel: what to decide to change, and what to leave intact in the timeline. Sebastian also has some misgivings: "It's about controlling something we obviously have no control over."

The less said about the ending, the better, because it's designed to spark reflection and debate. "When people finish watching the movie, I want them to have a conversation," said Bristol.

For all the tragic elements in his film, Bristol hopes it also sends a message of hope. "I want to tell people that what happened in the past is the reason you're here today," he said. "I wouldn't change anything in my past, [even though] I wish I'd done some things differently. If I didn't go through what I went through, I wouldn't have this success right now. So make the most of your future, because the future is wider than you think."

See You Yesterday premiered on Netflix last week and is currently available for streaming.

Listing image by YouTube/Netflix