At a fête to raise funds for a Polish school unpleasant mayor William Knight is electrocuted by a microphone. Valentine arrests his long suffering wife Eleanor after a screwdriver is found in her handbag but there are plenty of other suspects, including his young daughter and the secretary he sacked after their affair was discovered, whilst he was also accused of bribery and corruption. As Father Brown solves the mystery a magician at the fête turns out to be the husband,presumed dead, of his housekeeper Mrs McCarthy, who walked out on her decades earlier. Now dying he wants to return to her but she refuses him.