Six Against the Yard (The Detection Club) The Detection Club by Margery Allingham, Ronald Knox, Anthony Berkeley, Freeman Wills Crofts, Russell Thorndike, Agatha Christie

These are all short stories that have a killer in them. 

The stories are mysterious and not too long.  It amazes me how the killer can figure out how to do  it and not get caught.

I didn't always know who the killer was until the end.

It was an interesting read.