A Harper novel of suspense ( )

A fairly routine mystery novel with some interesting discursions on different interpretations of the same sets of actions. The hook for me was its being set in the Scilly Isles, largely on Samson and Tresco, with some action back in Hugh Town on St Mary's. This novel was published back in 1954, but the basic background to the islanders' lives and to the habits of visitors to the islands hasn't changed since that time. ( )