“BlacKkKlansman” is the most powerful movie of the year.

It’s based on a book by Ron Stallworth who, in the 1970s, became the first African-American hired by the Colorado Springs police department. One day, he sees an ad in the paper for the Ku Klux Klan, which is soliciting for new members. Thinking it’s a joke, he calls the number and leaves a message. To his surprise, he gets a return call from a local klansman, who doesn’t know that Ron isn’t white. Getting approval from his chief, Ron proceeds to infiltrate the klan to see what they’re up to.

How does a black man become a member of such a racist organization, to the point where he’s getting phone calls of support and encouragement from David Duke? That’s the so-ridiculous-it-can’t-be-true-but-is story, which has a whole new relevance in today’s environment, particularly after the white supremacists’ march — one year ago this weekend — in Charlottesville that devolved into violence. Towards the end of “BlacKkKlansman,” director Spike Lee includes footage of that horrible day, as well as Donald Trump refusing to denounce the neo-Nazis (“there were very good people on both sides”). There are other echoes of the past in calls to make America great again, take back America, etc.

Stallworth is played by John David Washington, one-time player for the St. Louis Rams, member of the “Ballers” cast, and, yes, son of Denzel. He’s terrific in the role, as is Adam Driver as Flip Zimmerman, a Jewish cop who helps make Stallworth’s ruse work. The supporting cast includes Steve Buscemi’s lookalike brother Michael as another Colorado Springs cop, the riveting Ryan Eggold as one of the worst Klansmen, Paul Walter Houser playing a dumb redneck akin to his work last year as Shawn Eckhardt in “I, Tonya,” Laura Harrier as a student activist Ron gets involved with, and Topher Grace as Duke. There’s even a cameo by Harry Belafonte.

Jordan Peele, fresh off the success of “Get Out,” was going to direct “BlacKkKlansman,” but he wisely chose to turn the project over to Lee, who has turned out a helluva riveting movie. Peele still gets a co-producer credit for a movie that’s funny at times, but also horrific in retrospect, especially since so much of the hatred that was spewed by those racists four decades ago continues today. As for Lee, it’s a perfect match for his style and voice, the best movie he’s made since “Inside Man” in 2006. It will have you leaving the theater both entertained and provoked.

I give “BlacKkKlansman” a 9.5 out of 10. It is my current leader for Best Movie of 2018.