
The recap below contains plot spoilers about Episode 3, "A, B & C." If you haven't seen "A, B & C" yet, you can watch the full episode online.
In an attempt to discover why No. 6 resigned from the Service, the new No. 2 uses a wonder drug to tap into his subconscious.
The Prisoner is the subject of an experiment to manipulate his dreams.
Why did the Prisoner (Patrick McGoohan) resign from his highly confidential job? The desperate efforts to extract the truth from him take a new turn when No. 2 (Colin Gordon) decides to take the risk of subjecting him to an experimental process developed by No. 14 (Sheila Allen) in which his dreams can be penetrated. Under the influence of a wonder drug, his subconscious thoughts can be converted into electrical impulses and finally into pictures on a television screen.
No. 2 is convinced that the Prisoner was going to sell out. He wants to know what he had to sell and who would have been the buyer. Computed research has boiled the potential buyers down to three people. His dreams must take them to meet each one in turn. "And then," No. 2 points out, "we'll know what would have happened if we hadn't got to him first."
The doped Prisoner is mentally transported to Paris and to one of the celebrated parties given by Madame Engadine (Katherine Kath). Pictures of Character A (Peter Bowles) are implanted in his mind.
But the outcome is a disappointment for No. 2. The Prisoner's actions indicate that he would never have sold out to Character A.
No. 14 says the risk is too great to give him a second injection immediately; another day must elapse. Twenty four hours later, the process is repeated. The Prisoner's subconscious mind again takes him to Engadine's party in Paris, and he meets Character B (Annette Carel). But even in his dreams, the Prisoner is suspicious, and No. 14 tries a new experiment by projecting her voice into his dream in the hope that he will answer questions and give himself away.
Again, the results are disappointing. It now remains for the Prisoner to be subjected to a third injection and meet Character C. But who is C? No. 2 doesn't know his identity.
Before the final experiment, however, the Prisoner, his suspicions aroused because of the marks of the drug syringe on his wrist, discovers the whereabouts of No. 14's laboratory and finds the third syringe.
Now forewarned, he can control his third "dream" in the way he wants, and he plays a cat-and-mouse game with No. 2, who is caught in his own macabre trap.