This mystery novel begins a new spin-off from a series Anne Perry has been writing for decades. Daniel Pitt is the son of an investigative husband-and-wife team that featured in the Thomas Pitt series. As this book opens, he is in his mid-twenties and just beginning a legal career. He's in the midst of one case in which the defendant seems headed for a guilty verdict, but Daniel gets him off thanks to some nimble deduction regarding fingerprints.
He is rushed to assist another lawyer on a case in which the head of his firm takes a special interest: a man on trial for the murder of his wife. When a guilty verdict is returned, the legal duo has 21 days to find cause for appeal, before the sentence of execution gets carried out.
This novel has well paced twists and turns and kept me quite interested. I have been a little annoyed by what I see as flaws in Anne Perry's writing in the past, but those tendencies are restrained in this book. Her characters tend to do so much introspection at every moment, and lace their dialogue with so much philosophizing and generalizing that the pace can get a bit sluggish. But in "Twenty-One Days," things kept moving pretty quickly to a satisfying conclusion.
The characters, some of which are likely being set up to become regulars in future installments, are likable and don't have unnecessary angst or manufactured conflict. Daniel Pitt's partnership with Kitteridge, a senior lawyer, has a few moments of tension between the older and younger man, but they manage to communicate fairly well, and overall it bodes well for a good partnership.
I will really look forward to the next book.

I was able to read this early thanks to NetGalley.