When council clerk Martin Barrett is shot dead, Barnaby and Jones discover he was an expert blackmailer. As they investigate which of his victims hated him enough to kill him, the trail leads to Fennacombe Bay. Why are Richard and Maggie Florian spending so much time at sea and could police committee chairman Sir John Waverley have a scandal in his past? With the help of a policeman turned fisherman, Barnaby takes to the waves to find out.