Retired hangman Henry Lee is celebrating but one of his last victim he pulled the noose on might had told him the name of the real murderer before he went down.
Now Lee is confronted by his mother, Iris still protesting her son's innocence and wanting to know what her son told Lee. Father Brown investigates the former hangman is poisoned and Iris is the main suspect. Meanwhile Mrs McCarthy is being romanced by a former policeman.
It is just a shame that the two story strands were always bound to get entwined meaning you get a good idea who a likely suspect is going to be. The perils of being a guest star in a mystery series.