It is quite difficult for me to review and rate this novel.
In terms of puzzle quality, ingenuity and structure, it scores well. There are two murders, one early on and the other, which will surprise some readers, at about halfway through.
Bathurst seems to make little progress, despite being convinced of the innocence of the man accused and tried for the first murder, that of a blackmailer. After the second death, the investigation moves on apace, and the solutions are rapidly found. I certainly found the second murder fairly easy to work out.
What sticks in my throat is that the perpetrator of the first murder is duly punished, while those responsible for the second apparently go scot-free, Bathurst effectively acting as judge and jury. I found this part of the solution repugnant. It is difficult to go fully into this without giving away important parts of the plot, but it certainly goes against any reasonable person's concept of justice and makes for a very unsatisfactory ending.
3.5 stars.