Mysteries and crime fiction have long been kept on separate shelves in the bookstores, divided from the safely ensconced literature section.
The thinking here, perhaps, is to prevent crossover, or even taint, between genres. But where to draw that line has always been problematic.
There's another trend which blurs it even more. Serious fiction writers have, from time to time, taken a crack at the crime novel, often under a pseudonym.
There are few more serious novelists writing today than John Banville. The acclaimed Irish writer's novel, "The Sea," won the Man Booker prize in 2005.
John Banville has now crossed that divide into crime fiction, writing his latest novel, "Christine Falls," under the name of Benjamin Black. MPR's Tom Crann spoke with Banville.