BBC radio 4 : Episode 3: The Hitchhiker

In The Hitchhiker, Andrew Pym, a successful author, is driving to London in his brand new BMW. He stops to give a hitchhiker a lift. Unwisely, he allows the man to persuade him to see if the car can go as fast as its manufacturers claim. Stopped for speeding, his details are noted down by a policeman who warns him to expect a heavy fine and sends him on his way. Blithely unconcerned at causing so much trouble, the hitchhiker starts boasting that he is engaged in a line of work that requires exceptional skills. And it's these skills that can get Andrew out of his present difficulty.

http://www.bbc.co.uk/programmes/b01pg3qr