And so although there are many things to love about An Old Betrayal, the seventh Charles Lenox mystery series written by Charles Finch, the development of several supporting characters is what makes this particular installment in the series stand out for me. In fact, it may be my favorite in the series thus far, though it may be more accurate to say it ties with A Burial at Sea.
Additionally, the book has several delicious sub-mysteries as well, all involving people in Charles' life. Finch's skill as a writer quietly shines here -- none of the subplots feel forced or shoehorned in, and one never gets the sense that characters appear simply because they are "fan favorites", which can sometimes happen when a series becomes more popular. The most interesting of these is a mystery of sorts that threatens Charles' career in Parliament.
A successful series installment makes the reader eager to read the next installment. When it comes to mystery series, for me, it also makes the characters seem like old friends you visit periodically. By that measure, this series is a resounding success.