The series follows an unnamed British agent (played by Patrick McGoohan) who abruptly resigns his job, apparently preparing to go on a holiday. While packing his luggage, he is rendered unconscious by knockout gas in his apartment. When he wakes, he finds himself held captive in a mysterious seaside 'village' that is isolated from the mainland by mountains and sea. The Village is further secured by numerous monitoring systems and security forces, including a mysterious balloon-like device called Rover that recaptures – or kills – those who attempt escape. The agent encounters the Village's population, hundreds of people from all walks of life and cultures, all seeming to be tranquilly living out their lives. They do not use names but instead are assigned numbers, which give no clue as to any person's status (prisoner or warder). Potential escapees therefore have no idea whom they can and cannot trust. The protagonist is assigned Number Six, but refuses the pretense of his new identity.