Tangerine is motivated by an insatiable desire for fidelity. “Fidelity” – we typically use that word in two contexts, marriage and sound reproduction. In both cases, the word refers to faithfulness to a source. In marriage, a fidelitous spouse maintains the stabilizing, life-giving, identity-granting union shared between two people. In sound reproduction, a recording has fidelity if it sounds very much like it did when it was produced.

Both shades of meaning apply to Tangerine, Sean S. Baker’s independent comedy-drama about a pair of transgender prostitutes searching West Hollywood for their pimp on a hot, L.A., Christmas Eve afternoon and evening. Tangerine premiered at this year’s Sundance Film Festival and is famous for having been shot entirely on a smart phone. That’s the kind of log-line that gets a film noticed, but unless the film is good, it’ll never be more than a bit of trivia. Tangerine is a great film. If you don’t mind the licentious subject matter—there will be more about the importance of that subject matter in a moment—you’ll forget you’re watching something shot on the device you might very well be reading this review on right now.

Tangerine’s two prostitutes, Alexandra and Sin-Dee are searching for their pimp, Chester, because Sin-Dee just learned Chester, who is also her fiancé, cheated on her while she was in prison for a month. And there’s Tangerine’s first insistence on the importance of fidelity. Chester hasn’t been faithful to Sin-Dee, and even though he’s a pimp and she’s a prostitute, fidelity matters, and there must be a reckoning. This main story is paralleled by the story of a married, Armenian taxi driver, Razmik, who picks up transvestite prostitutes while trolling the West Hollywood streets for fares. His reckoning is coming as well, and his, Sin-Dee’s, and Alexandra’s stories are headed toward an intersection from the moment the film begins. They eventually collide in one of the funniest scenes I’ve seen all year.

Tangerine is packed with characters and stories, and many of them seem random until you notice the fidelity through-line. Why does the story focus on transgender prostitutes? Perhaps it’s because their efforts to realize what they see as their true gender identity is an example of this ever-present pursuit of fidelity in all things. What are we to make of Alexandra’s lounge-show in the middle of the film, a performance she pays to put on? Perhaps this is an example of her being true to her deep need to express herself artistically even if it means she has to bear the entire cost of dong so herself (a compulsion familiar to artists of all ilk, regardless of their discipline). Razmik’s early scenes involve a carousel of taxi fares, and each of them fails, eventually, to hide who they truly are, how their days are going, and how they feel about riding in Razmik’s cab.

Tangerine’s second and overarching insistence on the importance of fidelity is tied to its smartphone production method, its subject matter, and its setting. Shooting a feature film on a smartphone grants the image a sense of authenticity distinct from the more polished and massaged images we’re used to seeing coming out of Hollywood. Tangerine feels like real life, because it looks like something you could have shot in real life, albeit probably without the same degree of skill. “Shot entirely on an iPhone 5s” is more than a gimmick; it’s a conveyor of meaning.

The film’s subject matter—West Hollywood prostitutes, their pimps and Johns, the multi-racial, multi-gendered, and socio-economically diverse makeup of the cast, and the typical struggles of all of the above—is faithful to the Los Angeles that actually exists. L.A. is many things, and this is a side of Los Angeles culture that is rarely filmed. Committing a culture to film, digital or otherwise, denotes importance. A movie is an evangelist for the worth of a particular group of people and their problems. If it’s filmed, it matters. Tangerine is funny and thrilling. It is also compassionate. By rendering this aspect of Angeleno culture faithfully, Tangerine is exhibiting fidelity to the real people like the fictional ones in its story.

Ultimately, Tangerine is a movie about people who are faithful to each other, who have compassion on each other, and who only get by because they look out for one another. That’s why it matters that the story takes place on Christmas Eve, a day typical reserved for families. These people are each other’s family. If the film skewers anyone, it skewers those who refuse to see Los Angeles and its people for who they truly are, the kind of person who looks at L.A. and focuses only on the palm trees, movie stars, and sunny weather and fails to see the true, more fascinating and beautiful Los Angeles standing on the street corner in broad daylight. Tangerine depicts this kind of self-imposed blindness as a destructive force that would break apart families, ersatz or traditional. Tangerine is full of broad characters, but it only laughs at the characters who focus on the glitter at the expense of the substance underneath. To love, after all, is to see clearly all of another’s beauty and ugliness and remain true, to maintain fidelity, nonetheless.