Mission: Impossible (1966) : 7x3

The Syndicate plans to finance the head of the army's takeover of his country in return for the right to operate the country's vices. The IMF team must intercept the safe deposit key before it reaches the general. Willy replaces a crewman aboard the yacht, but can't find the key and is discovered. He is forced overboard, almost drowns, but escapes and helps warn the team. Jim, Barney and Mimi craft an elaborate plot to convince the bad guys' courier to reveal the location of the key.