“BLACKKKLANSMAN” — 2 1/2 stars — John David Washington, Adam Driver, Laura Harrier, Topher Grace; R (language throughout, including racial epithets, and for disturbing/violent material and some sexual references); in general release

People are going to remember two things about Spike Lee’s “BlacKkKlansman.” The first is its crazy true story — with plenty of strong language — about an African-American detective in 1970s Colorado who infiltrates the local Ku Klux Klan. The second is the way Lee slaps a shocking coda on the end of that story that turns his film into a polarizing statement on contemporary politics.

The first part really is a riot. John David Washington plays Ron Stallworth, the first African-American police officer in Colorado Springs. We meet Stallworth as he arrives on the job to a host of raised eyebrows, and it’s soon apparent that he’ll be dealing with racial tension from within the department as well as around the community.

Unsatisfied with his initial assignment in the evidence room, Stallworth makes a big step towards his goal of being a detective when he is sent undercover at an event sponsored by the local Black Student Union, where activist Stokely Carmichael (AKA Kwame Ture, played by Corey Hawkins) is scheduled to speak.

Here Stallworth meets Patrice Dumas (Laura Harrier), the attractive president of the union, and to keep his romantic chances with her alive, he keeps his identity secret.

The story picks up momentum soon after, when, in the course of an investigation, Stallworth contacts the local Ku Klux Klan chapter on the phone. The department suspects the Klan is involved in illegal activities, so Stallworth pursues the investigation, with the Klan assuming he’s just another fellow supremacist.

As the investigation deepens, eventually intertwining the film’s different subplots, Stallworth pairs up with a white detective, Flip Zimmerman (Adam Driver), who poses as Stallworth when meeting face-to-face with the local Klan leadership. Zimmerman befriends a trusting Walter Breachway (Ryan Eggold), and a much more suspicious Felix Kendrickson (Jasper Paakkonen), while on the phone, the real Stallworth contacts prominent Klan leader (and eventual failed presidential candidate) David Duke (played with eerie effectiveness by Topher Grace).

“BlacKkKlansman” is pretty enjoyable as a low-key police procedural, but its primary function is to put a comic bull's-eye on the backside of white supremacy. In some ways, it plays like a non-musical version of “The Producers,” with the clandestine Klan subbing for “Springtime for Hitler.” The portrayals of Duke and co. are almost that cartoonish, and at times, even sad, such as with Ashlie Atkinson, who portrays Felix’s misguided wife Connie.

As an additional effect, Lee gives the film a slightly grainy quality, which makes it feel like a product of its time. Still, the story that surrounds “BlacKkKlansman” has less to do with the film’s subject, and more to do with how once its story is resolved, Lee tacks on a surprise ending that is bound to polarize audience reaction.

At the risk of a minor spoiler, “BlacKkKlansman” makes several critical allusions to President Trump and his “America First” platform throughout the film, and the shock ending takes that subtle cautionary message and turns it into a bludgeon. Details will be withheld for the sake of discretion, but audiences should know the final reel contains some disturbing violent content that, along with R-rated language throughout the movie, is primarily responsible for the film’s rating.

For many on either side of the ideological divide, the ending will be a bold final validation of sentiments they already held, even if objectively it forsakes filmmaking subtlety to turn persuasion into provocation. It makes the movie more memorable, and that may very well be Lee’s goal. But it also means most people’s takeaway from “BlacKkKlansman” will be more rooted in personal politics than the substance of the film, and that feels like a shame.

Content advisory: “BlacKkKlansman” is rated R for strong language throughout, including racial epithets, and for disturbing/violent footage and some sexual references; running time: 135 minutes.