The village of Midsomer Barton is celebrating Oak Apple Week when a local single mother, Marion Slade, is found drowned in the village stream. It looks like suicide, and that she was driven to it by grief over the death, eight years before, of her daughter, Bella, a local beauty pageant winner. Barnaby investigates and is shaken by two villagers who look like murder victims from his past. Then another body is discovered and it appears that the festivities have stirred up a cocktail of adultery, contempt, unrequited love and revenge in the village. And it all appears to center around Bella Slade.

The elderly Sir Freddy Butler has invited both his ex-wives, Annabel & Lucinda, to stay with him and his current wife, Tara. When he dies suddenly of a heart attack, the bitter rivalry between the three and Sandra, the wife of his heir, comes to the surface, with murderous consequences. To solve the mystery, Barnaby must unravel paternity questions about some of the residents of the hall, and find the legendary missing emeralds.

Barnaby and Jones investigate the shooting of a blackmailer, Martin Barrett. But he had so many victims, they are spoiled for choice for a suspect. Then one of his victims, Sir John Waverley, gets another demand. The trail leads them to the seaside and diving for treasure on an uncataloged wreck.

Barnaby's mother-in-law comes to visit, and insists on being taken to the village of Broughton, which has seen a war between the sexes for decades. During this year's traditional fair, elderly women's campaigner Mildred Danvers is murdered. And then the misogynist vicar, the Rev Anthony Gant, is murdered during a bizarre traditional event that forms part of the proceedings. Is this an evening of the score, or is another long-standing feud responsible?

Frank Hopkirk, an environmental adviser on the proposed site of a controversial Goodfare supermarket in Elverton-cum-Latterly, is found stabbed to death in an old farm building on the site. Barnaby & Jones question locals on both sides of the debate over the plans, and find that Mr Hopkirk had extra-curricular dealings with a number of the local ladies and their businesses. But which one of these caused passions to be stirred up to such a murderous extent?

The Midsomer Worthy local amateur choir includes Joyce Barnaby & Dr Bullard amongst its members. Their conductor, Laurence Barker, has a bitter feud with a rival. Following a rehearsal for the regional Four Choirs competition, the lead tenor, Connor Simpson, dies mysteriously.

Annie Woodrow, a charity worker from Midsomer Malham, is standing trial for killing her best friend, Frances Trevelyan, in a case that Barnaby had investigated ten months previously. But he becomes increasingly unsettled that the prosecution's case doesn't match the facts. Barnaby & Jones enlist the help of key witness Mrs Beverly in a risky entrapment to find out what really happened. Jones's promotion to Det Sgt comes through at the same time.