One of Our Spies Is Missing

U.N.C.L.E. agents Napoleon Solo and Illya Kuryakin are sent to Europe where a scientist's age-reversing machine is in danger of being seized by T.H.R.U.S.H. spies.
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.