It's a picture of a futuristic Britain and Alex leads his 'droogs' (gang) around the city beating up old homeless guys and robbing and raping younger women.
Eventually his luck to avoid the law runs out and he is captured after his droogs stitch him up and he is led away to prison. While there he learns of a breakthrough treatment that will 'cure' him of performing bad deeds.
After undergoing the treatment, Alex is released from prison with his ordeal far from over.
By today's standards however, the imagery in A Clockwork Orange is fairly tame by contemporary comparison (Saw, for example is far more gory). The debate that the film evokes though is still current, raising huge issues about the morality of forcing immoral behaviour from criminals by using psychological methods.
Often the film itself is lost amongst its controversy but once this is stripped away, A Clockwork Orange shows a unique view into the mind of Stanley Kubrick.His vision of a futuristic Britain is realised on the big screen, from the horrifically white bar where the droogs meet, to the muggy streets of the city and finally a chair with a lid. Despite this there a signs of contemporary Britain in the buildings, their doors and human fashion.
The theatrical music revolves heavily around the undertones of Ludwig van Beethoven's Ninth Symphony which is loved by Alex and becomes a part of his downfall.
Overall, a visionary, and slightly disturbing image of a futuristic Britain.