Over the last couple of decades, American have been immersed in the phenomenon of the Christmas romance movie, which are all very much alike but people watch them like they are consuming comfort food. A similar but much older genre of Christmas entertainment can be found in the United Kingdom, where the Christmas murder mystery is a thing. Murder mystery novels rose in popularity in the early 20th century, as they put the reader into the role of detective, trying to figure out whodunnit. Anything that popular is bound to eventually have a Christmas version, and that happened in the 1930s, and again, and again.
The Christmas mysteries are now known as "cozy crime" stories, because the elements are so familiar, and the plots follow a standard crime investigation that leads to the murderer's reveal at the end. While murder and Christmas aren't the most natural pairing, such novels have become beloved in the land that gave birth to them. Every year, mystery fans look forward to the Christmas stories they've become used to. Read how this strange but common genre of fiction came about at Atlas Obscura.