The Spook Who Sat by the Door changes registers a few times throughout; it begins on very procedural terms, leavened throughout by very wry black comedy. A black man, Dan Freeman (Lawrence Cook), excels and attains token placement in the CIA, where his 'Uncle Tom' tactics get him ahead. Lots of small gestural and behavioral beauties--like when Freeman is called last-minute from his job as Director of the Reproduction Department (he makes photocopies in a back room all day, the only job they're willing to give the black hire) to give a tour of CIA facilities to a bunch of white Senators--he advances his hand for a shake ever-so-slightly before dropping it again, acknowledging that he'll get no fraternal greeting.
The film then goes into a different kind of procedural mode, from institutionally-critical to productive: Freeman makes contact with a militant black gang in Chicago, asserts himself as its ring leader; they become an active Black Panther organization (in all but name): our hero's really a radical, and nobody suspects because they don't think the black militants are capable of intelligent resistance.
And from this point there's a certain docudrama urgency to the film (e.g., amazing crowd control and shooting in a neighborhood riot sequence). The Spook Who Sat by the Door has a variegated style and a loose linear structure: a lot of registers to work even (even broad slapstick once or twice), and it succeeds in most of them.
Hogan's Heroes actor Ivan Dixon had something to him as a director, though his directorial work was almost all in television I think. 'Subject for Further Research.'