Within the human character, the line between good and evil is a thin and waving one.
The formula used by The Whistler is a highly flexible one, but if you are a show lasting thirteen years without summer breaks, you occasionally need to break or subvert the formula. "Christmas Bonus" has a structure very much like a typical Whistler tale: someone's done wrong, the net tightens, something triggers a shift, they get their comeuppance. But it takes it in a different direction from the usual, recognizing that there is another story in the vicinity, and that sometimes the more interesting story is not how the fallen get their punishment, but how the unfortunate are saved from a fall. We all need a little unexpected help sometimes, a little protection from ourselves and the terrible mistakes we can make. And a Christmas message of being able to rise above the darkness inside packs a special punch coming from a series that so often focuses on the darkness itself.
Mike Cobb fell in with the wrong crowd when younger and did time for it. Now, he has been trying to go straight and build a solid life with the woman he loves. But when the store he works at has a series of thefts that certainly indicate an inside job, and he is the obvious suspect, he is locked in a chain of events that can take him down a very dark road. Merry Christmas, Mike; the police detectives will be coming to talk to you....
You can listen to "Christmas Bonus" at the Internet Archive (number 63). The episode has a famous mistake -- the announcer announces the title as "Lie or Consequences" rather than the real title, "Christmas Bonus".