Detailed Synopsis

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.

Barnaby and Jones investigate the murder of Martin Barrett, a council clerk shot dead in his cottage at midnight. A painting in an auction catalogue leads the police to pub landlord Jack Fothergill. His cleaner Ruby Wilmott clearly hates Barrett.

Barrett had a phone number for Richard and Maggie Florian on his blotter but they tell police they spent the weekend at their boat at Fennacombe Bay. Under questioning, Jack admits he sold a painting at auction to avoid paying death duties for his father. Barrett found out about the fraud and was blackmailing him.

A receipt in Barrett's car links him to Fennacombe Bay so Barnaby takes Joyce to the coast. Jones visits another possible blackmail victim, Sir John Waverley - a farmer and chairman of the police committee, who once ran a refuge for teenage girls. Jones thinks Waverley, who hopes to become High Sheriff, is hiding something.

Coastal fisherman and former Hong Kong police officer Peter Hatchard takes Barnaby out to Richard and Maggie's catamaran but there are no signs of smuggling or drugs to indicate they might be more of Barrett's victims. Ruby finds a shotgun in the pub and fires it accidentally during a row with Jack. And Waverley opens his door to find a note from a new blackmailer.

Hatchard tips off Barnaby when the Florians arrive unexpectedly at Fennacombe Bay, while Jones discovers Richard was recently fired from his job at an oil company.

Cully's schoolmate Hayley, who once resided at the home, gives Waverley a glowing report - but the next morning Waverley admits he is being blackmailed, although he has done nothing. He agreed to pay up in a bid to save his election chances.

Ruby is found out to be a thief and Barrett was blackmailing her. The police set a road trap and discover Barrett's blackmail accomplice is none other than Hayley.

When Waverley takes an overdose, Barnaby rushes him to hospital where Jones spots Richard Florian - his wife Maggie has suffered decompression sickness after a dive. What is hidden in the sea and have the Florians killed Barrett to keep it quiet?