Peckover and the Bog Man — Michael Kenyon

Inspector Henry Peckover has cheerfully accompanied his wife Miriam to Inverballoch and the 170th Robbie Burns celebration in this wee corner of the Scottish Highlands. Little does he know what he's gotten himself into...
Sir Gilbert Potter, Britain's most eminent archaeologist, has invited Miriam Peckover to be guest chef, and Henry predicts a night of wine, women, and song. At first, all goes smoothly. Miriam's haggis is delicious, the Scotch flows freely, and Peckover even manages to understand some of Burns' poetry before going to bed a contented man. But his slumbers are rudely interrupted by the news that Sir Gilbert Potter has been murdered.
Granted Potter was a pompous bore, but who could have wanted him dead? Might the killing be connected with the dig Sir Gilbert was leading up at Dundrummy Castle?