In 1989, Spike Lee dropped a racially charged bomb at the Cannes Film Festival when he debuted his Palme d’Or-nominated masterpiece, Do the Right Thing. Almost 30 years later, he did nearly the same thing when his tonally unclassifiable BlacKkKlansman premiered in May. One of only two American films in competition, the audacious adaptation of retired police officer Ron Stallworth’s autobiography took home the festival’s Grand Prix award.

Although it’s far from a comedy, producer Jordan Peele (writer/director of last year’s Get Out) encouraged Lee and co-screenwriter Kevin Willmott (who co-wrote Lee’s Chi-Raq) to relieve some of the tale’s tension with disarming humor, the better to ease the audience into the heavy issues the film deals with, including the legacy of hate that groups like the Ku Klux Klan have kept alive in this country.

Lee’s film might be set during the late ’70s, but he never explicitly states the year, which only accentuates the ever-more-apparent fact that the America he’s portraying—a country where white cops are free to target black citizens, while the politics of the day embolden racists to thrive—might as well take place in present day.

Taking a hard look at how little we’ve progressed, Lee furthers his long-standing examination of the clash between love and hate, which was earlier exemplified by the knuckle rings that Radio Raheem (Bill Nunn) brandished on his fists in Do the Right Thing as an explicit callback to Robert Mitchum’s knuckle tattoos in 1955’s Night of the Hunter. The culture war that’s bubbling to the fore right now has been brewing for years, and with BlacKkKlansman, Lee indicts the racist ideals that are being legitimized by the actions of the current administration. It’s not for nothing that his latest film is opening in the U.S. on Aug. 10, the one-year anniversary of the white nationalist rallies in Charlottesville, Virginia.

But again, Lee’s freewheeling biopic isn’t a completely somber affair. Rather, it’s the closest he’s made to a mainstream crowd-pleaser in years. Based on some “fo’ real, fo’ real shit,” as an opening credit announces, BlacKkKlansman follows Stallworth (John David Washington of HBO’s Ballers, who kicked off his career at age 8 with a bit part in Lee’s Malcolm X) as he infiltrates the KKK. The first black detective in the Colorado Springs Police Force is thrilled that he’s been able to pass for white while speaking on the phone with Walter Breachway (Ryan Eggold), head of the Klan’s local chapter, but Stallworth soon realizes that his charade can only go so far. So, when he’s offered an invitation to meet and discuss membership in “the organization,” Stallworth enlists white detective Flip Zimmerman (Adam Driver) to pose as “Ron Stallworth,” Cyrano-style. As Zimmerman plays the public half of Stallworth at Klan meetings, the real Ron develops a stranger-than-fiction phone relationship with none other than David Duke (a three-piece-suit-wearing, mustachioed Topher Grace), then-Grand Wizard of the Klan, who never even considers that his new “friend” might not be white.

This entire setup affords Lee to delve into explorations of race that go beyond simply the color of Ron’s skin; Flip, you see, is Jewish, a sin that he’s forced to hide from his new “friends,” particularly Felix (Jasper Pääkkönen), a violent racist who’s determined to get “Ron” to prove he’s not a Jew during more than one of the film’s excruciatingly tense scenes.

In a sense, both Ron and Flip are “passing,” and though Flip tells Ron that he never gave much thought to being a Jew, now he’s “thinking about it all the time.” It’s during scenes like these—and others involving the mismatched partners’ hard-nosed captain (Robert John Burke)—that Lee gets to scratch a buddy-movie itch, while gleefully borrowing the aesthetics of 1971’s Shaft and 1972’s Super Fly, courtesy of Marci Rodgers’ costumes, Chayse Irvin’s 35 mm cinematography and Terence Blanchard’s funk-infused score. Stallworth even stops to discuss the finer points of these blaxploitation classics while wooing Patrice Dumas (Laura Harrier), a student activist he’s also been deceiving due to her distrust of “pigs.”

This romantic subplot is indicative of Lee’s tonal shifts in storytelling, some of which don’t work, but most of which do. The parallels and nods to current events elicit big laughs, such as when someone observes that a racist like Duke could never be elected president. Still, the triumphant final scenes come perilously close to ringing false.

Perhaps realizing that a neat bow is not what his movie needs, Lee resists easy closure, finally allowing the real world to intrude in one of his signature montages that closes the curtain; you’ve likely seen most of the archival footage Lee deploys here, but after some of the most entertaining and exuberant interludes he’s committed to film in years, the ending comes like a punch in the gut. It’s a clarion wake-up call the likes of which haven’t been heard since the climactic moments of Lee’s School Daze three decades ago.

BlacKkKlansman ★★★ 1/2

Starring John David Washington, Adam Driver, Topher Grace, Laura Harrier, Ryan Eggold, Jasper Pääkkönen, Corey Hawkins, Paul Walter Hauser, Ashlie Atkinson, Michael Buscemi, Alec Baldwin and Harry Belafonte. Written by Charlie Wachtel, David Rabinowitz, Kevin Willmott and Spike Lee, based on the book Black Klansman, by Ron Stallworth. Directed by Lee. At Assembly Row, Boston Common, Coolidge Corner , Fenway, Kendall Square, South Bay and in the suburbs.