RATING |

While the Charlottesville riots — which happened a year ago this weekend — provided further evidence that hate groups like the Ku Klux Klan are no laughing matter, it is also true that racists sometimes leave us with few other options.

In Spike Lee's BlacKkKlansman, for instance, there is a scene of white supremacist leader David Duke (Topher Grace) pontificating about his unerring ability to detect black dialect, unaware he's on the phone with an undercover black police officer.

It's funny, and like many things in the movie, shockingly true. All part of the amazing, only-in-America (and not always in a good way) story of Ron Stallworth, a black police detective who infiltrated a Colorado Springs chapter of the Klan in the 1970s.

Stallworth (John David Washington) was new to the job when he spotted a Klan recruiting ad in the paper and made contact, leaving his department phone number. When it rang, he was so surprised to be greeted so cordially and so immediately that he blurted out his real name.

>> READ MORE: 'BlacKkKlansman's' star John David Washington on what it's like to compete with his dad Denzel at the box office

Lee maneuvers his camera to capture the comic dynamics of the scene — he starts on Stallworth's face, then reverses point-of-view to show a roomful of veteran detectives, laughing at Stallworth's rookie blunder. But it's a gaffe that sets up the incredible story that follows — Stallworth continues to answer the phone, while white undercover cop Flip Zimmerman (Adam Driver) goes to the meetings, and gradually insinuates himself with the Klansmen.

Stallworth and Zimmerman work so well that their composite "Ron Stallworth" is ultimately offered the job of chapter leader. This seems like an absurd Hollywood invention, but it happened. Many of the story's apparently preposterous turns are taken from real life. Stallworth really did develop a long-term telephone "friendship" with Duke (whose pseudo-corporate unctuousness is captured nicely by Grace).

And when Duke came to Colorado Springs for a Klan rally, Stallworth really was assigned to his security detail, leading to a nose-to-nose confrontation that is also drawn from real life. (Ditto an earlier scene of Stallworth having a one-on-one with Kwame Ture, a.k.a Stokely Carmichael, played by Corey Hawkins, while working undercover).

So Duke gets punked, and while he has it coming, it's also clear that Lee knows the risks involved with making a Klan leader a figure of ridicule. These were (are) dangerous people.

Stallworth's investigation ended with the exposing and re-assigning of Klan members who were active-duty military (two guys ended up in Greenland, the loneliest outpost the Army could find). But others reformed in another group that later murdered Denver radio host Alan Berg (itself the inspiration for the Oliver Stone film Talk Radio).

Lee conjures a bombing (in reality there was a conspiracy to bomb a gay bar, but no explosion) to dramatize the dangers involved. Later, as Lee shows Duke heading a Klan ceremony, he cross-cuts with a black man (Harry Belafonte) describing in detail a real-life lynching.

Lee makes his point: The danger is real. But the celebrity cameos can also work to disrupt the story's flow — Alec Baldwin makes a baffling one-off appearance as a racist trying to make a propaganda film. These elements, and frequent references to contemporary politics, sometimes make it hard for BlacKkKlansman to live and breathe in its chosen period.

Lee also provides running commentary, sometimes detached from the narrative completely, about racist imagery in Hollywood films, quoting from Birth of a Nation and Gone with the Wind, adding a debate on the semiotics of blaxploitation movies. The latter surfaces in a conversation between Stallworth and his girlfriend (Laura Harrier), a student activist, which is more smoothly integrated into the story.

The title promises something of a biography, but I left the movie wanting to know more about Stallworth. We know what he did, but getting a deeper read on the man proves elusive. Recent interviews show him to be a fearless, ferociously independent fellow who was always steered resolutely by his own lights. He was driven to be a police officer at a time when that was not a popular, natural career choice for black men.

Why? Washington is left to fill in the blanks, and is not always successful. But he's an engaging performer, good at creating energy with other actors — Grace, Driver, and Robert John Burke as his police captain, who sees Stallworth's potential to be the force's  "Jackie Robinson." Why? Because while everything else was going on, Stallworth also integrated the department.

BlacKkKlansman. Directed by Spike Lee. With John David Washington, Adam Driver, Laura Harrier, Topher Grace, Robert John Burke, and Corey Hawkins. Distributed by Focus Features.

Running time: 134 minutes

Parents guide: R (violence)

Playing at : Area theaters