The Black Widow (1951)

Robert Ayres is driving down a country lane when he comes across someone laying in the middle of the road. Thinking it is someone who has been hit by a car he stops to see if he can help. What he gets for his efforts is a vicious belt to the head from a lead cosh. He is then relieved of his wallet and his car. Several minutes later having somewhat recovered, he staggers to a nearby farmhouse and collapses.