The Spook Who Sat by the Door (1973)

In order to improve his standing with Black voters, a white Senator starts a campaign for the CIA to recruit black agents. However, all are graded on a curve and doomed to fail, save for a soft-spoken veteran named Dan Freeman. After grueling training in guerrilla warfare, clandestine operations and unarmed combat, he is assigned a meager job as the CIA's token black employee. After five years of racist and stereotyped treatment by his superiors, he quietly resigns to return to his native Chicago to work for a social services agency...by day. By night, he trains a street gang to be the vanguard in an upcoming race war, using all that the CIA has taught him.