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Breakthrough is the eighth episode of the fourth season of The F.B.I., and the ninety-fifth episode overall.
Guest Stars: Bill Zuckert (Joe Darwin), Peter Mark Richman (Vincent Gray), Grant Williams (S.A.C. Kirby Greene), John Ryan (Ernie Flood), Jeff Davis (Bobby Pollack), Joe Perry (Stan Jason), Rose Hobart (the Maid), Edward Andrews (Vic Russell), Dorothy Provine (Irene Minnick)