I have fallen in love with the Wrexfrod & Sloane series of books by author Andrea Penrose. It’s a bit of Regency romance, a bit of mystery, a bit of thriller, combined with a science lesson. Murder on Threadneedle Street is the tenth book of the series, and the author has promised that there is still more to come, for which I am grateful. This isn’t the place to start the series if you haven’t read any of the books yet. There is a fair amount of backstory as to how Charlotte and Wrex met and fell in love, as well as how they acquired the menagerie of friends who make up their inner circle. I do think it’s a great story that builds on what has happened already in the series.

Wrex and Charlotte have found themselves with custody of four young adults. Two of the boys were street urchins Charlotte befriended before she ever met Wrex. One came to live with them when he was left an orphan and was rejected by some of his family due to his mixed race. In the last book, Wrex found out that his late estranged father had another child, a girl, who is also now without a parent to care for her. They are all in their young teenage years or that “tween” age. Both Wrex and Charlotte come from the nobility, although neither of them has much to do with English society except for when they have to. They are trying to make sure the four wards get proper educations, and in that regard, try to gear it towards what interests each of them.

Fletcher Campbell was the drawing instructor for the young boy they call Hawk. He was found murdered in what appears to have been a robbery turned violent. Hawk is quite upset and asks if they can investigate his death. Both Wrex and Charlotte are hesitant, but agree that there can’t be any harm in asking a few questions.

Boy, were they wrong. They uncover ties to counterfeiters who were hanged almost 10 years earlier for their crimes. At this time, each of the banks in England issued their own banknotes, making it hard to keep track of what was real. The idea is to come up with a standard currency for the entire country. With a contest in the offering to create a banknote that is not able to be counterfeited, are there people who never answered for their crimes now coming out of the shadows?

The mystery in Murder on Threadneedle Street was a bit convoluted, but also a good one. Penrose writes these books with plenty of research into the topics at hand, and it’s interesting to see all of the scientific advances happening at this time. Wrex has always been interested in metallurgy, and his knowledge here comes into play in the forming of the plates to print bank notes. The typical formula for the metal is too soft to hold up under that kind of pressure, but new discoveries are being made. Penrose takes a few liberties with the actual history to make it fit into her story. You can read about what’s true and what is embellished to fit in the story in her afterword. I have found all of them quite interesting.

With their charges getting older, Wrex and Charlotte struggle with protecting them. They agree to Eddy, Wrex’s sister, and Raven being allowed to have pistols and to be instructed in their use. Charlotte also frets that Eddy is nearly of an age to make her debut and all that goes along with it. The characters are aging throughout the stories, which is nice to see. I hate books or series that expect us to believe so much happens to the characters in the space of a short period of time.

It’s also nice to see more about some of the peripheral characters. Cordelia barely appears here, and I had an inkling why early on. Penrose gives us a lot of Baz’s backstory. He’s the trusted local mortician that Wrex has relied on to take care of the various victims they’ve found throughout the years. There’s a lot of intrigue and suspicion surrounding him, which created some real conflict.

The amount of research Penrose has done into the times and the technology she focuses on is incredible. I like books that make me think, and this one fulfills that in many ways. At times, it does seem to get bogged down in scientific terminology, but that’s the point. Most of the population wouldn’t know how to do what is discussed in Murder on Threadneedle Street in regard to creating new banknotes that are not so easily copied. The concept of using a special lathe to create repeated patterns that can’t easily be duplicated by hand is not something most people will have knowledge of. The result is a very educational mystery.

I loved the style and story of Murder on Threadneedle Street. It’s a great addition to the series, and it moved the characters ahead a bit as well as introducing new scientific discoveries and concepts. I recommend the book for people who have already read the series. If this sounds intriguing, go back and start the series at the beginning. You won’t regret it.

Note: Thank you to NetGalley, Kensington Publishing, and author Andrea Penrose for the advance reader copy of this book. This review will also be posted on NetGalley. What follows is my unbiased review of the book.

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