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.

NYPD detectives Bonaro and Madigan lose their guns to fugitive Barney Benesch. As compensation, they are given a weekend to bring Benesch to justice. While they follow various leads, Police Commissioner Russell goes about his duties, including attending functions, meeting with aggrieved relatives, and counseling the spouses of fallen officers.