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.
Writer: Howard Rodman
Director: E. Darrell Hallenbeck
Story: Henry Slesar
Director of Photography: Fred J. Koenekamp
One of Our Spies Is Missing