The Wiki plot write-up gives spoilers but this is the first bit of it:
Stranded after a car accident in the Fenland village of Fenchurch St. Paul on New Year's Eve, Lord Peter Wimsey helps ring a nine-hour peal on the church bells overnight after William Thoday, one of the ringers, is struck down with influenza. Lady Thorpe, wife of Sir Henry, the local squire, dies the next morning and Wimsey hears how the family has been blighted by the theft 20 years previously of a valuable emerald necklace which was never recovered. The family's then butler, Deacon, and his accomplice from London, Cranton, were convicted and imprisoned.
Episode 2 is here:
Thereafter you'll need to watch on YT itself - they're all laid out.
The major theme running through it is the Spanish Flu of 2018, with one sub-theme being the way God's vengeance or fate or karma catches up with wrongdoers, even after they seemingly get away with it. Bellringing is another and the life and feel of the times is another.
An interesting aside is Sayers and feminism, which the egregious Harriet Vane represented but:
Sayers refused to be identified as a feminist stating, "I am afraid—that I was not sure I wanted to “identify myself,” as the phrase goes, with feminism, and that the time for “feminism,” in the old-fashioned sense of the word, had gone past."... assertions such as, “a woman is as good as a man” or the tendency to "copy what men do," may in fact subvert the point an advocate of women's rights would want to prove in the first place.
Thank goodness for that eh?