Tonton Streaming Mission: Impossible (1966) S1E25 - Shock

Enemy operative Kiri has kidnapped U.S. envoy Carl Wilson and has an imposter, Gort, who is impersonating him to discredit a U.S. trade agreement. The team have to rescue Wilson and foil the impersonation before Kiri kills Wilson. Cinnamon impersonates Wilson's niece while Willy kidnaps Gort and Briggs-as-Wilson takes Gort's place, pretending to be Gort. The team put Gort in an asylum and give him electro-shock to scramble his memories, then claim he is is a delusional accountant. Under the threat of more electro-shock, Gort tells them the full details of his delusion: that he's to kill an American official and leave Wilson to take the blame. Barney and Willy replace the unconscious Wilson at the reception with a drugged Gort set to look like a suicide, then Briggs-as-Gort-as-Wilson takes a shot at the official. Briggs returns and reveals that "Wilson" is actually Gort, who was in Keri's employ.