Cat's Paw (S05E15)

Larry Collier, a newspaper editor and Barney's brother, is murdered while investigating a connection between corrupt police chief Abbott and Corley, the leader of a gang who hides his criminal dealings behind an insurance business. To get closer to Corley, Barney, who has a shady background as an accountant, saves Corley’s secretary, Millie, leading to his hiring. Barney sets up Corley's assistant, Goslin, to appear disloyal by planting money, while the IMF stages a fake seance to scare Goslin into resignation using damaging evidence. Jim captures Goslin with a crucial codebook and leverages it to pressure Abbott into supporting him as a mob boss, then bribes Corley's guard to eliminate Corley. After saving him, Barney confronts Corley, who, facing Jim's threat to expose him to Abbott, decides to testify against him.