As presidential campaigns begin to test unifying messages for 2020, they might find inspiration in a little-known story of interracial coalition-building arriving in movie theaters this spring. I know the story of “The Best of Enemies” because, as a young white man from the South, I was adopted into the freedom movement by Ann Atwater, the African American community organizer whose vision for fusion politics is its driving force. Because I knew Grandma Ann and the beloved community she welcomed me into, I know that true multiethnic democracy is possible. In the midst of the identity crisis we face as a nation, the organizing tradition that Atwater embodied is the strong medicine we need: It has the potential to break through the lie that has convinced us that for one community to win, another must lose.

“The Best of Enemies” tells the unlikely story of how Atwater (played by Taraji P. Henson) came to work with C.P. Ellis (Sam Rockwell), a local leader of the Ku Klux Klan, to develop a plan for school desegregation in Durham, N.C. Atwater and Ellis had spent years rallying their competing bases to out-shout each other in public debates over civil rights. But in 1971, when the AFL-CIO received a federal grant to help Durham comply with the 1954 Brown decision that had outlawed segregation in public schools, Atwater and Ellis each agreed to co-chair the process in order to keep the other from controlling the outcome. In the process of working together, they discovered something neither of them had really understood before: They were both poor, and a system that kept them poor was their common enemy.

When I met Atwater three decades later, I asked whether she would teach me what she had learned about community organizing. “Well, it’s pretty simple,” she said. “I listen to you until I learn what you want, then I help you get it. When we get halfway to what you want, I’ll tell you what I want.” Atwater’s fusion organizing philosophy makes her story — and that of “The Best of Enemies” — different from much-derided movies such as “Green Book,” in which dignified black people raise the consciousness of white people who remain at the center of the story. When genuine fusion organizing works, everyone benefits and everyone changes.