There’s nothing the British enjoy more than a cozy little murder. Whether on Sunday night or Christmas Eve, Britons from all walks of life luxuriate in watching a wealthy dowager sip a poisoned cocktail, or seeing a spinster take a knitting needle to the throat. For decades these grisly events have been reliably provided by the Agatha Christie television adaptations that have become a highlight of British national holidays, regularly drawing millions of viewers. Yet recently this blood-flecked tradition has been shaken to its very foundations.

The person doing the shaking is Sarah Phelps, the writer of a quintet of mini-series—And Then There Were None, The Witness for the Prosecution, Ordeal by Innocence, The A.B.C. Murders, and, on Amazon Prime this month, The Pale Horse—that have roiled Christie traditionalists and casual TV viewers alike. On the face of it the shows would hardly appear to be controversial. They’re beautifully filmed and populated by such fine character actors as John Malkovich, Bill Nighy, and Toby Jones. However, Phelps’s ruthless reconstruction of Christie’s work—her insertion of sex scenes, drug-taking, and language most foul—has caused a national crisis on the order of Brexit.