Radio has to be one of the most un-cinematic things on the planet; it's a guy sitting in a booth for four hours talking into a microphone, or maybe playing some music. And yet radio has a kind of special magic about it. A person's voice comes sailing through the airwaves and landing in our homes, and it has the power to captivate, to soothe and to make sense of the world. Radio has appeared in a surprising number of good movies: Wolfman Jack and Stephen Wright, respectively, provided atmosphere in American Graffiti (1973) and Reservoir Dogs (1992), Robin Williams brought humor to the troops in Good Morning, Vietnam (1987) and Christian Slater brought hope to high school students in Pump Up the Volume (1990).

It's probably a great deal more difficult to make a movie about podcasting, and so with her new film Talk to Me, director Kasi Lemmons (Eve's Bayou, The Caveman's Valentine) returns to the past for the story of Ralph "Petey" Greene (Don Cheadle), an ex-con who became one of Washington DC's most recognizable personalities in the 1960s and all the way up to his death in 1984. Lemmons starts her movie with a bang, with Petey's signature line: "Wake up, Goddammit!" as Dewey Hughes (Chiwetel Ejiofor) rolls out of bed, puts on his suit and makes an excursion to prison to visit his brother (Mike Epps). Lemmons intercuts Dewey's progress while Petey "raps" about imprisonment. Dewey may be free, but he's trapped, too.

Dewey works at soul radio station with an all-black staff, but run by the white, sympathetic E.G. Sonderling (Martin Sheen). Their star DJ is the smooth, sexy Nighthawk (Cedric the Entertainer), who shows up to work wearing furs and walking his various small dogs. Nighthawk burns candles while on the air, while the lightweight, coma-inducing Sunny Jim Kelsey (Vondie Curtis-Hall, Lemmons' husband) has the morning slot. Petey manages to get himself released from prison, moves in with his loyal girlfriend Vernell (Taraji P. Henson) and jive-talks his way into a job. Even though Petey and Dewey instantly clash, and despite testing the FCC with his language, Petey becomes an instant hit. From there, Lemmons traces Petey's history as his star rises, Dewey becomes his manager and their relationship deteriorates.

Lemmons' major achievement is the way that she has been able to trace nearly 20 years of history while still allowing the film to live in its current moment. Most films of this type, even classics like Francois Truffaut's Jules and Jim (1961), have a tendency to hit only highlights, like a stone skimming over the water but never getting wet. Lemmons allows her film to slow down and bathe in real-time emotions. Lemmons has always been good at this type of pause and reflection, most notably in her extraordinary debut, Eve's Bayou (1997), which is surely one of the greatest achievements in African-American cinema, as well as her follow-up, the misunderstood The Caveman's Valentine (2001). The first film had a kind of voodoo mood, while the second employed "magic realism." This new one lives through the spirit of radio.

This time, however, Lemmons' film may stir up some enthusiasm over its amazing performances. (Lemmons was an actress herself in small roles in The Silence of the Lambs and Hard Target among other films, before turning director.) In many Hollywood films, a "crazy" character meets an "uptight" character and they wind up benefiting one another, but those films rarely break away from caricature. Here, both Petey and Dewey come from real places. When Petey does something outrageous, it comes from his character, rather than a need to make the audience laugh. When Dewey does something uptight, it makes sense; he truly does not understand how his behavior looks on the outside. (In one scene, he confesses that he has based his entire professional life on Johnny Carson.) Even Taraji P. Henson, who gets the "girlfriend" role here, finds moments of grace within her character's rather predictable arc (and her great wigs, ranging from "Foxy Brown" to Beyonce-like).

Lemmons' tour-de-force moment comes in the movie's centerpiece: the 1968 death of Dr. Martin Luther King. Witnessing the angry rioting in the streets, Petey climbs into his booth and begins the long process of talking the city down, sharing in their pain and trying to re-establish the ideas that King fought for. Done a thousand times before, it's a sequence that could have gone south quickly, but Lemmons saves it with her confident, almost dreamlike rhythms and Cheadle's superior performance. The sequence finishes off with Sam Cooke's "A Change Is Gonna Come," which has already been established as an important song to both Petey and Dewey. Like magic, the song floats through the air, bringing understanding and hope to everyone who listens. It has been made special through radio, and now it gets a new layer, being married to Lemmons' images. It will never sound the same again.