A society wedding in Sherborne Abbey is interrupted when the organist is found murdered in the organ loft. The finger of suspicion is pointed at the mysterious 'Lady in Blue'. Inspector Loveluck and his team uncover a huge fraud, involving not only the wealthy members of Sherborne town but also the seemingly harmless but eccentric 'Last of the Summer Wine Investors Club'. When the most prominent member of Sherborne society disappears and Inspector Loveluck's sergeant is kidnapped, the stakes become terrifyingly high. A rollercoaster of events takes them to Spain in the search for the coded diary and the only person who can decode it seems to outsmart Loveluck at every turn.