The Black Klansman is a feature film of the blaxploitation

Blaxploitation

Blaxploitation or blacksploitation is a film genre which emerged in the United States circa 1970. It is considered an ethnic sub-genre of the general category of exploitation films. Blaxploitation films were originally made specifically for an urban black audience, although the genre's audience...

 genre originally released in 1966 under the name I Crossed the Color Line. Set during the struggle for Civil Rights, the film tells the story of an African-American man, played by Richard Gilden, who disguises himself as a white man to join the Ku Klux Klan

Ku Klux Klan

Ku Klux Klan, often abbreviated KKK and informally known as the Klan, is the name of three distinct past and present far-right organizations in the United States, which have advocated extremist reactionary currents such as white supremacy, white nationalism, and anti-immigration, historically...

to seek revenge on Klan members who killed his daughter.