I tried to read this book a couple of times years ago, but now that I have read all the Poldark books, I thought I would try again. I saw immediately why I couldn't get into it before: the first page is almost unintelligible, full of somewhat obscure London and opera references. I laughed about it this time, as I have learned over the years to stick with bewildering sentences and foreign names until they (usually) give way to more understandable content. Once past the opening pretentiousness, I caught the rhythm of the story and settled down to read what was labeled "a novel of suspense." I don't think I would categorize it as "suspenseful," although the last few pages were probably intended to covey a sense of anxiety. I think it was more of a cobbled together love story/mystery that made quite a few leaps in logic while jumping to unsupported conclusions.
The plot was pretty thin: former lover murdered while husband of heroine was coincidentally in the same area. Through extraordinary set of circumstantial evidence, he is put on trial for his life.
The characters were flat and one-dimensional. So really all that drove the book along was the writing style. And, as I mentioned, one had to get past the gobbledegook before the style became readable. But once there, author Winston Graham is a formidable storyteller who makes us want more. The book held very few surprises, but it was a quick, entertaining read. And clean!