Whilst temperance campaigners,led by fervent,ex-alcoholic parson Norman Grigor,protest against the Midsomer Abbas May Festival,the body of Peter Slim,a revenue inspector investigating illicit stills,is found dumped in a cider vat. The murder weapon,an apple tree harvester which shook him to death,belongs to boozy cider mill owner Anthony Devereux, a man with something to hide though he denies murder. Then Barnaby discovers a secret connecting Slim to a village girl and a party to that secret is murdered. As pub landlord Samuel Quested leads the villagers in the revival of an old fertility custom Barnaby and Jones find themselves in peril during the night of the stag.