This episode may be a little bit confusing to watch as to follow Number 6 and Number 12 both played by McGoohan. By watching it on video, I finally wasn't confused in the end. The mystery code Schizoid Man is released by the end of the episode with Rover killing number 12. It was the only episode that Number 6 said Rover by name.
This type of episode is exactly what I love about "The Prisoner"--a surreal, mind-boggling stress test of psychological torture, with a top-notch, brilliant script. For my money, I'm not sure if any show since has been as tightly plotted and scripted; the dialogue in any episode of "The Prisoner" is always witty and tense, but in "The Schizoid Man", it is a joy to behold. Frankly, considering that we, the viewers, are never truly in doubt as to which man is Number Six, everyone involved does a perfect job of convincing us of the existential horror of not knowing who you are. The ending of the episode is a high point for the series.