The King Died and Then The Queen Died

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