Dead Men at the Folly (not to be confused with Agatha Christie's Dead Man's Folly) dates from 1932. My copy is the US edition, emblazoned with the legend 'A Dr Priestley Mystery', even though the crusty old professor doesn't play much of a part until the story until the closing scenes. The majority of the detective work is conducted by Superintendent Hanslet of the Yard, ably assisted by a capable local cop called Inspector Richings. One entertaining feature of the story is the way the cops defer to Priestley, following his instructions to the letter once he stirs himself to take an interest in the mystery.
The story opens shortly before Christmas. A chap on a motorbike gets lost in rural south west England and finds himself close to a slightly sinister tower, which turns out to be known as Tilling's Folly. What is definitely very sinister is that he also stumbles across a dead body close to the tower.
There is some confusion about the identity of the deceased, which isn't cleared up for some time. Without giving too much away, two men in the story bear a very strong resemblance to each other. Now I thought this was a pointer to a particular kind of plot twist, but it proved not to be, although that strong resemblance does play an important part in the storyline. Hanslet soon thinks he's solved the case without needed to rely on Dr Priestley. But, surprise, surprise, he is mistaken.
This is a solid and readable story, but I felt that it suffered somewhat because of a lack of suspects. I had a pretty good idea of whodunit from about halfway through the book. Overall, I'd say this isn't one of Rhode's best books (although some Rhode fans rate it very highly), and it's definitely not as lively as the Christie with the similar title, but it's still a sound mystery, in which he draws on his personal experience in engineering for one particular murder method. Worth a read? On balance, I'd say yes.