One of Our Spies Is Missing (1966)

A biochemist develops a process that reverses ageing but, when he disappears, it’s up to Napoleon Solo and Ilya Kuryakin to recover or destroy the process before it falls into the hands of the THRUSH.
E. Darrell Hallenbeck
Robert Vaughn, David McCallum, Leo G. Carroll, Maurice Evans, Vera Miles, Ann Elder, Yvonne Craig, Bernard Fox, Harry Davis, Monica Keating, Dolores Faith, Ahna Capri, Cal Bolder, James Doohan, Ollie O’Toole, Anthony Eustrel, Richard Peel, Barry Bernard, Robert Easton
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