This fourth story in the series is quite the thriller. It kept me turning pages to see what was going to happen next.
Although those in law enforcement in this age are against the idea of any sort of 'espionage' against it's own populace, and the idea of a 'plains clothed' policeman is untrusted and unliked by it's leaders and citizens, there are some times when ways into the underground of London's criminal class can not be breached by those in uniform. Police Commissioner Sir. Richard Mayne finds himself having to ask for help from sources he neither likes, nor trusts, but it may be the only way to stop a killer, and possibly a revolution. When the criminals follow no rules, and the Police are expected to be above board in all things, can the public really be protected? It's an interesting dilemma for the times.
This story brings back ex-detective Williamson and his friends Dyson, Benjamin and Cullen to work together behind the scenes to stop a mysterious killer, and a stop plot against the government itself. The four men, who have forged a friendship and a working relationship of sorts through the first three books, find themselves being asked to step in to help solve a case where only those who can traverse the darker side of London can find the answers. Detective Inspector Albert Newsome is also involved, but as a working Detective his view of the help given by untrusted outsiders only aggravates his need to prove himself, collides with his ideology of police work, and interferes with his personal vendetta against an old adversary. He provides even further complications in solving the case by his unwillingness to accept help and his need to prove himself.
The case soon becomes personal for Williamson,Dyson, Benjamin and Cullen as the four men find themselves targets and in deadly danger along the way. These are men who've come to rely on each other through past adventures, and who are finding that following rules isn't always the best way to get at the truth.
I highly recommend reading the first three books, "The Incendiary's Trail", "The Vice Society", and "The Thieves Labyrinth" in order to get a complete feel of the story line. There are many things that are introduced in earlier books that continue here, and to miss those will be missing a good deal of the atmosphere of the story.
I'm very much enjoying this series, and look forward to more adventures by the four men involved.