The series opened with the hero, played by McGoohan?, apparently a worker in some government intelligence building in London having a violent argument with his superior and resigning. Returning to his flat, he is quickly packing his possessions, until knockout gas piped into the room renders him unconscious. On awakening, he finds himself in a strange village of pseudo-mediterranean architecture (the series was filmed at Portmeiron? in Wales), filled with other people, also being held captive. No-one has a name, and they all have numbered ID badges. Our hero is number 6: his real name is never mentioned anywhere in the series. HIs resignation, drugging and awakening was shown briefly in the opening sequence of all the following episodes, with the following exchange:
.... followed by laughter from Number Two.
The village is ruled by Number Two: a different person helds that number in every episode. Number One was never seen. Throughout the series, Number Two was tried to find out why Number Six resigned: A variety of interrogation, drugs and mind control techniques are used, all ultimately unsuccessful. Number Six's repeated escape attempts were monitored in the underground control room, and foiled by the automatic guards, balloon like devices that engulf and suffocate him. (The producers actually used weather ballons for the effects). The series featured quite surrealistic story lines, including secret agent film parodies and an apparently successful escape.
The series attracted considerable attention: rather like the later Twin Peaks, many viewers had no idea what was going on in the episodes, but watched it compulsively anyway. There is a Prisoner Appreciation Society devoted to the series, and a Prisoner memorabilia shop in Portmeiron.