The Spook Who Sat by the Door is a novel by Sam Greenlee, first published in 1969, and also a movie released in 1973. It dramatizes the C.I.A.'s history of training people and groups who later use this knowledge against the agency--essentially Trojan Horse revolutionaries who beat the system at its own game. 

When liberal Chicago senator Hennington is facing a tight re-election campaign, his wife suggests he accuse the C.I.A. of racial discrimination as a way to win the Black vote. Hennington does, and his campaign is victorious. However, at the CIA, only one man, Dan Freeman, who is secretly a black nationalist, successfully completes the training process. Now the first Black man in the agency, he is given a plum desk job where his main duty is to demonstrate the "diversity" at his workplace. As soon as his training is completed, he resigns and returns to work in social services in Chicago, where he organizes a group of young Black men and teaches them everything he learned at the C.I.A. They call themselves the Freedom Fighters, "the Urban Underground of Black Chicago." "What we got now is a colony," says Freeman, "what we want is a new nation."

"One of the things I was saying with that book," Greenlee told The Crisis, "is that gangs could become the protector of the community rather than the predators."

The title of this book refers to Freeman's very visible position at the C.I.A. "Spook" is both racial slur against Blacks, and a slang term for a spy.