The setup for this episode is okay: Number 2 decides to lock himself up with Number 6 for a week and see if he can get him to tell why he resigned.
The next 45 minutes are almost intolerable, however. It seems like Leo McKern and Patrick McGoohan are improvising their dialog, which usually consists of Number 2 saying a word and then Number 6 saying a word. "Time." "Good." "Fleet." "Dead!" "Dead?" "Doornail." etc... For the most part the episode is incoherent with the occasional brilliant light, which quickly becomes lost in more incoherency. The verbal duel seems to be between the individual and the "needs" of society, with honor being lost when the individual is asked to conform to society (see the USSR).
Despite a worthy topic, I just couldn’t take the presentation, which is why I give this the lowest rating for the entire 17 show series. The early shows in The Prisoner are snappy and riveting, but the later episodes show some weakness - probably because McGoohan went away to film Ice Station Zebra in the middle of production, and frankly they needed him there to continue working on scripts. I doubt they had a script ready when it came time to film this one.