The plan to save the Elizabethan stately home Vormer House by selling part of its deer park for a golf and hotel complex has a mixed reception from local politicians, and others. Merchant banker Mark Treasure is financial advisor to the property group behind the development. He and his wife Molly drive up to attend the Thatchford town meeting called to air the project. Scandalous accusations are made, but worse is to come when a party in the house where the Treasures are staying is interrupted by the police, come to question the local MP after finding his glamorous secretary ghoulishly murdered.
While the probable suicide of the likeliest suspect promises a swift and easy solution to the case, it's too much so for the conscientious DCI Furlong, especially when another less explicable death occurs. But when Treasure discovers that Furlong is about to arrest someone who the banker is positive is blameless, he sets up his own investigation.
Planning on Murder is the sixteenth, and penultimate, Mark Treasure mystery - and is bursting at the seams with mystery, comedy and Williams' sparkling wit.