Number Six is a former agent with British Intelligence.
What his real name is remains a mystery, probably even to himself although that is not quite completely settled. That issue is but just one of many, many items in which the truth is neverl quite arrived at. It is the struggle of the man everyone calls Number Six to find out who he is, or was, where he is, other than just in the Village, and what do the people running the encampment, the Guardians, want of him.
One thing that Six definitely knows is that he was an agent with British Intelligence and apparently a very good one. He grew tired of the lying and sneaking and double-dealing that he was forced to do on a daily basis and one day walked into his director's office and handed in his resignation. According to the novelization, he was planning to retire to Wales to do whatever he wanted as long as it was not being a spy. When he was preparing for his departure, he is rendered unconscious.
Awakening in what appears to be a pleasant small English village, albeit with some strange varieties of architecture, he is confused and understandably upset. Where is he and how did he get there and what is going on? Those were his first questions and as time go by, no answers to these queries comes to him, only more questions. Remembering that he had once been very good at his job and determined to get free, the life of Prisoner Number Six is one devoted to breaking free from an idyllic landscape where every move he makes is monitored and occasionally he is pulled in for the strangest forms of interrogation. Is the questioning they do of him because they are the enemy trying to plumb his knowledge or are they his own people seeing if he would break?