Guilt by Association — Jean Davidson

When freelance editor Kate Nesbitt sublets her flat in Edinburgh to American Charlene Oatman, and goes away on holiday, she little realises that she will become involved in a case of murder…

Kate is horrified when a few weeks after her return to her flat, Charley's body is found in the cellar of the building. She had been strangled. But why when Kate told her dearest friends, Ginnie and Rory, about the discovery did Ginnie not tell her she knew Charley?