PARK CITY, Utah — Too often, the focus at the annual Sundance Film Festival is on stars we already know telling stories we've already heard, usually involving white upper-middle-class ennui. But Tangerine, which made its debut at the fest this weekend, is none of those things.

It takes almost no time at all for the movie to announce itself as one of the most vital films at Sundance this year. It opens on transgender prostitutes Sin-Dee (Kitana Kiki Rodriguez) and Alexandra (Mya Taylor) splitting a doughnut at Donut Time, a real shop in Los Angeles, on Christmas Eve. Sin-Dee just got out of a 28-day stint in jail, and she is anxious to tell her best friend news about her boyfriend Chester (James Ransone), who also happens to be their pimp.

But before Sin-Dee can make her announcement, Alexandra blurts out that Chester's been cheating on her — and with a cis woman. That is all the spark Sin-Dee, who speaks in a torrent of lisp-y fury, needs to send her charging out of Donut Time on a rampage to find Chester. As she tears through the particularly seedy stretch of Santa Monica Boulevard that Donut Time calls home, the screen explodes with a blast of vivid color and angry techno music, the camera swooping past Sin-Dee to take in the strip malls, pawn shops, and liquor stores that line the street. Alexandra, who is as calm and measured as Sin-Dee is a dervish of scattered energy, rolls her eyes and chases after her friend, pleading with her not to cause drama, knowing full well that is exactly what is going to happen.

And at the end of that roughly five-minute sequence, I was grinning with delight.