This note on Amazon gives some background:
"Throughout her illustrious career as the Queen of Crime, P. D. James was frequently commissioned by newspapers and magazines to write a special short story for Christmas. Now, for the first time, four of the best are collected here. In “The Twelve Clues of Christmas,” James’s iconic Scotland Yard detective, Adam Dalgliesh, is drawn into a case that is pure Agatha Christie. In “A Very Commonplace Murder,” a respectable clerk’s secret taste for pornography is only the first reason he finds for not coming forward as a witness to a terrible crime. “The Boxdale Inheritance” finds Dalgliesh reinvestigating a notorious murder at the insistence of his godfather—only to uncover the darkest of family secrets. And in the title story, a bestselling crime novelist describes the crime in which she herself was involved some fifty years ago.
Playful and ingenious, shot through with narrative elegance and sly humor, The Mistletoe Murder is a treat for P. D. James’s legions of fans—and anyone who enjoys the pleasures of a masterfully wrought whodunit."
