James' gloss on Forster

"In his book Aspects of the Novel. E.M. Forster writes:

'The king died and then the queen died' is a story. 'The king died and then the queen died of grief' is a plot... 'The queen died, no one knew why, until it was discovered that it was through grief at the death of the king.' This is a plot with a mystery in it, a form capable of high development.

To that I would add, 'Everyone thought that the queen had died of grief until they discovered the puncture mark in her throat.' That is a murder mystery, and it too is capable of high development.
--P.D. James. Talking About Detective Fiction.