At the end of “Malcolm X,” Spike Lee’s formidable bio-pic of 1992, we see a bunch of schoolkids, standing up in turn to announce, “I’m Malcolm X.” Thus is the hero of the film, played with charismatic self-command by Denzel Washington, presented as the Spartacus of his people. Now, twenty-six years later, in Lee’s latest movie, “BlacKkKlansman,” one of those kids, John David Washington, gets a leading role for himself. He is the son of Denzel, and, like his father before him, he owns the screen. Both are graceful, thoughtful, and unrushed, keeping their wits at the heart of an inflammatory tale—not to douse it but to control the course of its fury. If there is a Washington method, it is this: stay cool, and feed the flame.
The title…