The 17 episodes tell the story of an un-named spy (McGoohan always denied that the central character was his Danger Man character, John Drake) who, in the event of his retirement from the secret service, finds himself confined in an incomprehensible coastal village filled with seemingly happy people each identified by numbers rather than names.
Many aspects of the series have become firmly established in popular consciousness; the village itself (actually Portmeirion in North Wales), the Ron Grainer theme, 'Rover' the inflatable guard ball and the two key quotes from Number 6...
and of course...
So, below is the pilot episode 'Arrival'. I'm not sure how many of the other 16 episodes are available online but the series has been released in box sets a number of times and is absolutely well worth your money.
Buy it here - The Prisoner - The Complete Series [DVD] 
Below that is a shortish documentary tracing the origin and legacy of the series.
hope you enjoy.
Be seeing you.
The Prisoner - Arrival by tvchannels