I am a great fan of the Charlotte and Thomas Pitt series, and own them all. This seems to me to be the weakest of the collection. The plot convolutions are ingenious and well up to Anne Perry's usual standard, but about one-third of the way through I found myself, to my amazement, losing interest. [Spoiler alert!] Charlotte's expedition to Ireland, masquerading as Narraway's half-sister, didn't convince me: passing herself off as an O'Neil while amongst the O'Neil clan and a society acutely aware of kinships and loyalties seemed extremely unlikely, and Narraway's escape from prison culminating in a confession from the killer while his pursuers obligingly waited outside the door so that they could overhear everything also strained belief. The final third of the book, with Charlotte and Thomas back in England and unraveling the convolutions within the Special Branch, was far better, although there was little to explain why apparently loyal civil servants such as Croxdale and Gower should have become revolutionaries. As an aside, it was good to see the delightful Gracie back in a cameo, and I hope that her replacement, Minne Maude, will be a permanent addition to the cast!