I don't know if you have heard about what happened in England a while ago, but I feel is echoes you story slightly.
An old man was walking down a dark and empty road, being followed by two teenagers in black clothes, hooded.
After several turns and after several hundred metres the old man realised he was being followed, he walked down a dark alley. The teens followed, to see the old man facing them.
The old man then knocked them both out.