Like "Moonlight," "Beale Street" — the title of which is explained in an opening crawl — defies simple description. But it is, at its core, a love story, albeit one where the central players face formidable challenges predicated on the notion that life — especially as it pertains to young members of the black community — isn't always fair.Unfolding in part through flashbacks, the movie maintains the novel's voice through the narration of Tish (newcomer Kiki Layne, in a breakthrough performance), who has grown up in Harlem and, at the age of 19, fallen in love with Fonny (Stephan James, also featured in the Amazon series "Homecoming").Fonny, however, is in jail, having been arrested for a crime he didn't commit, when Tish realizes that she's carrying his child. The pregnancy produces a mixed response from her parents (Regina King, "Fear the Walking Dead's" Colman Domingo) and his (Michael Beach, Aunjanue Ellis), though they rally around the notion of trying to find a way to exonerate Fonny, despite the hurdles that the system throws at them."Beale Street" thus unfolds on parallel tracks, alternating between the current situation that Tish faces and the arc of their romance, which makes the idea of the two being kept apart — other than longing visits through prison glass — all the more painful.The simplicity of the concept belies the depth of emotion involved, the almost hypnotic tone (again augmented by Nicholas Britell's musical score), or the sobering idea that the unequal justice regarding poor minority youth that Baldwin — the author and civil-rights activist — addressed in the '70s remains a heated topic of conversation today.The movie works so well because of its attention to detail, unwillingness to embrace easy answers and resistance to painting with a too-broad brush. When the couple has trouble finding a landlord who'll rent to them, or encounter a racist cop, they also find moments of kindness and grace — including a white landlord who says all he cares about is seeing people who are happy together."If Beale Street Could Talk" portrays Tish and Fonny's fleeting happiness but also doesn't sugarcoat the impediments to it created by a system that treats young blacks as less than. Its director, meanwhile, has served notice — after the heady glow of "Moonlight" — that in terms of impeccably crafted drama, he's by no means a one-hit wonder."If Beale Street Could Talk" premieres Dec. 14 in the US. It's rated R.