An elite covert operations unit carries out highly sensitive missions subject to official denial in the event of failure, death or capture.
The show is about a team of secret agents called the Impossible Mission Force, or the IMF, who go on covert missions to fight and defeat syndicate crime lords and evil dictators. Each week the team leader gets his assignment from a tape recording left at an isolated location. He then assembles his team of specialists from a photo dossier, cuts ahead to one final briefing, then moves out into the field. The IMF team is typically composed of the 'Master of Disguise', the 'Femme Fatale', the 'Technical Genius', and the 'Strongman'. However, they bring in additional specialists as necessary, anyone from a safe cracker to a contortionist to a memory expert.

The team uses advanced technological gadgets, disguises, drugs, psychological manipulation, and a series of elaborate ruses to break into impenetrable safes, dispose dictators, set two bad guys against each other, and so on. If they can't get the villain punished for a crime he committed, they frame him for something he hasn't done or trick him into shooting another bad guy. In the end the team quietly slips away in a vehicle, their mission completed.

Although the formula varied only slightly from time to time and very little was ever revealed about the team members' background, the show proved popular enough to run seven years and outlast the other spy shows of the era.